Blennius spp See Blennies

Blyth, Edward English naturalist (1810-73), based in India from 1841 to 1862, and who, during that period, responded to many of CD's queries on plants and animals.

Blyth is much acknowledged as a source of information throughout *Descent and Variations, notably on the variability of domestic mammals and birds, but also including carp (Correspondence, Jan. 23, 1852). In fact, he is one of the authors most cited by CD (Sheets-Pyenson 1981;Tort 1996,p. 346). Thus, it is difficult to accept the notion, put forward by Eise-ley (1959), that Mr. Blyth's contribution to CD's work was deliberately obfuscated (see Smith 1960,1968 for a cogent refutation).

Even more preposterous is the notion that Blyth - who believed in the fixity of species -was the real source of CD's major insights,

C Hypsoblennius sordidus (Blennechis ornatus, Plate XVII), specimen from Coquimbo, Chile. D Auchenionchus microcirrhis (Clinus crinitus, Plate XVIII), specimen from Coquimbo, Chile. E Spotted robust triplefin Grahamina capito (Tripterygion capito, Plate XIX), from Bay of Islands, New Zealand.

particularly into *natural selection (Sheets-Pyenson 1981). Indeed, the material assembled by Eiseley to support this notion - justly forgotten articles by Mr Blyth - show that he did not come even close. However, Blyth did provide CD with information relevant to this book, and so we end this entry on a positive note. (See also Altruism; Bats).

Bonito A common name applied to a number of tuna-like fishes, including Skipjack Katsu-wonuspelamis (Linnaeus, 1758). As CD mentions 'bonitos' in the context of a *food web involving *flying fishes, we may cite *Giinther (1880, p. 458), who confirms that bonito "eagerly pursues the Flying-fish, and affords welcome sport and food to the sailor".

Bony fishes The most diverse and speciose of fishes, earlier reported to appear 'suddenly' in the fossil record (highest fish in Old Red Sandstone; Notebook C, p. 257). If true, this would have posed a problem for CD's gradualist theory: The case most frequently insisted on by palaeontologists of the apparently sudden appearance ofa whole group of*species, is that of the *teleostean fishes, low down, according to *Agassiz, in the *Chalk period. This group includes the large majority of existing species. But certain *Jurassic and *Triassic forms are now commonly admitted to be teleostean; and even some palaeozoic forms have thus been classed by one high authority.

If the teleosteans had really appeared suddenly in the northern hemisphere at the commencement of the chalk formation, the fact would have been highly remarkable; but it would not have formed an insuperable difficulty, unless it could likewise have been shown that at the same period the species were suddenly and simultaneously developed in other quarters of the world. It is almost superfluous to remark that hardly any fossil fish are known from south of the equator; and by running through Pictet's Paleontology it will be seen that very few species are known from several formations in Europe. Some few families offish now have a confined *range; the teleostean fishes might formerly have had a similarly confined range; and after having been largely developed in some one sea, have spread widely.

Nor have we any right to suppose that the seas of the world have always been so freely open from south to north as they are at present. Even at this day, if the Malay Archipelago were converted into land, the tropical parts of the Indian Ocean would form a large and perfectly enclosed basin, in which any great group of marine animals might be multiplied; and here they would remain confined, until some ofthe species became adapted to a cooler climate, and were enabled to double the Southern capes of Africa or Australia, and thus reach other and distant seas (Origin VI, pp. 285-6; Pictet 1853-4).

The last paragraph shows CD accepting a notion - that continents change positions relative to each other, break up and reassemble - which many geologists bitterly opposed until the advent of the theory of plate tectonics (Wegener 1966; Le Grand 1988). Also, this paragraph captures the broad outlines of how that part of the Tethys Sea overlapping with what we now call Southeast Asia became the world's hottest spot of marine, and especially teleostean, biodiversity (Pauly and Froese 2001). How could we here follow up on all of this?

Boxfishes Fishes of the Family Ostraciidae, characterized by a bony carapace encasing the body, hence their common name.

The family, which occurs throughout the Tropics, is represented here by Ostracion punc-tatus Bloch and Schneider 1801, sampled by CD in *Tahiti, "where it had previously been observed by Captain Cook" (Fish, p. 158).

Note that Jenyns initially identified this species as Ostracion meleagris Shaw, 1796 (in

Shaw and Nodder 1789-1813), a different species (Fish in Spirits, nos. 1325,1326).

Brains Fish have small, simple brains, especially *Pike (see plot in *FishBase), but this is no reason to agree with Brulle (1844), who suggested that their brains, and other complex organs, develop before other organ systems in the course of their ontogeny.

This gave *Huxley an opportunity to write one of his devastating critiques, here in a letter to CD: "The heart of a Fish is very simple as compared with that of a Mammal & a like relation obtains between the brains of the two - if Brulles doctrine were correct therefore the Heart & Brain of [. .] the Fish would appear at a later period relatively to the other organs than those of the Mammals - I do not know that there is the least evidence of anything of the kind - On the contrary the history of development in the Fish & in the Mammal shews that in both the relative time of appearance of these organs is the same or at any rate the difference if such exists is so insignificant as to have escaped notice [. . .]. The animal body is built like a House - when the judicious builderbegins with putting the simple rafters -According to Brulles notion of Nature's operations he would begin with the cornices, cupboards & grand piano." (Correspondence, July 7, 1857).

To which CD quickly agreed: Your instances of Heart & Brains of Fish seems to me very good (Correspondence,July 9,1857).

Branchiae Gills or organs for respiration in water (Origin VT,p. 431). Branchiae work by exposing a respiratory surface to a water flow, this surface being equipped for gas exchanges (O2 in, CO2 out).

However, branchial surfaces cannot, for compelling reasons of geometry, grow as fast as the mass (of body tissue) that requires oxygen and produces carbon dioxide, and in water-breathers respiratory surface area per unit of body mass always declines with increasing body mass (Pauly 1981,1997,1998). This leads to strong constraints on the life history and size of fish (see Oxygen).

Bream Common name of Abramis brama (Linnaeus, 1758), a member of the Family *Cyprinidae.

Bream, also known as 'Carp bream', can reach over 80 cm and live in Eurasian rivers, from 40° to 75°N. They are mentioned only once by CD, along with the *sex ratios offishes.

Breed A lineage of domesticated animals. CD used the word *race to refer to what we now call a breed (see also Carp, Goldfish).

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