April 28, 1905.] 



SCIENCE. 



655 



well informed, but his logical faculty and 

 taxonomic tact will be disputed by some at 

 least. 



The ' sixteen species ' recognized are 

 grouped under two genera — -Branchiostoma, 

 ' having biserial gonads and symmetrical meta- 

 pleura ' and Asymmetron ' with uniserial 

 (right) gonads and asynunetrical metapleura.' 

 One of the species referred to Branchiostoma 

 is the B. pelagicum. According to the orig- 

 inal describer ' buccal tentacles are absent/ 

 and this statement has been corroborated by 

 all subsequent observers; the last examiner of 

 the species (G. H. Parker, in November, 1904) 

 had an ' exceptionally well preserved specimen ' 

 and could ' confirm the statement of most 

 previous writers that oral cirri are absent.' 

 Parker was also, like C. F. Cooper, ' unable 

 to find any evidence of branchial apparatus.' 

 Furthermore, the gonads, though in two rows, 

 ' are often so closely pressed together near 

 the median plane that they there seem to 

 form a single median row.' Surely a species 

 distinguished by such trenchant characters 

 and also distinguished by its pelagic life is 

 entitled to distinction from all its fellows ! 

 Owen and the old naturalists generally con- 

 sidered the development of the mouth as ' a 

 longitudinal fissure with subrigid cirri on 

 each side ' to be an ordinal character of the 

 ' Cirrostomi ' named for Branchiostoma. Un- 

 questionably the character is of generic value 

 at least, and the form differing so decidedly 

 from it may be ranked not only as the type 

 of a distinct genus (Amphioxides), but dis- 

 tinct family (Amphioxididse). The details 

 of the oral structure, however, remain to be 

 made known. 



A flagrant violation of a principle of 

 nomenclature adopted by all learned societies 

 may next be noticed. The name Asymmetron 

 has been adopted for all the species ' with 

 uniserial gonads.' Now, Asymmetron was 

 not named till 1893, and long before (1876) 

 Peters had named a genus Epigonichthys for 

 a species which is believed by the author to 

 be congeneric with Asymmetron. If such 

 were the case, the prior name, Epigonichthys, 

 should of course have been used for the genus. 

 As a matter of fact, however, some natural- 



ists at least will adopt the names Epigo- 

 nichthys and Asymmetron, as well as Par- 

 amphioxus, for special species or groups of 

 species thrown together in Asymmetron. It 

 may be added that the fact that Peters did 

 not appreciate the proper generic characters 

 is not a necessary corollary of the question at 

 issue; he gave the name in connection with 

 an undoubted species and tried to define it. 



V. 



The ' Craniata,' or rather the pisciform 

 craniates, of course are the chief subjects of 

 the volume, the ' craniata ' being equivalent 

 to all the vertebrates of the old naturalists be- 

 fore the recognition of the Branchiostomids. 

 The.se are considered under two classes, (1) the 

 Cyclostomata and (2) the Pisces. The former, 

 and of the latter the Elasmobranchii or 

 Selachians, and the Ganoids of the Miillerian 

 system, have been treated by Professor Bridge; 

 the Teleosts are summarized by Dr. Boulenger. 

 The elaborate chapters on the anatomical sys- 

 tems and organs are also by Professor Bridge. 



On the whole, the chapters on anatomy and 

 physiology are apt and as full as could be rea- 

 sonably expected in a volume of the series for 

 which it was prepared. That on ' the 

 skeleton ' (Chapter VIIL), however, is in- 

 sufiicient in view of the extreme importance of 

 the various osseous elements in the determina- 

 tion of the relationships of all fishes. All 

 the non-teleost fishes might be lost and their 

 loss made good, numerically, by the dis- 

 coveries of a single year, yet all the space 

 that is devoted to the skeletology of a teleost 

 fish is less than ten pages (pp. 205, 211-216, 

 237, 240, 246) ; the species selected, the trout, 

 is also not typical, a far better representative 

 being the one chosen very many years ago by 

 Cuvier and retained by Giinther — the perch. 

 The nomenclature of the bones is that current 

 for a number of years past in Europe. Long 

 ago, however, Sagemehl expressed doubt 

 whether a single bone of the fish's skull was 

 really a homologue of any in the terrestrial 

 vertebrates. We fully share in that doubt, or 

 rather belief, but for the present may retain 

 the time-honored names derived from mam- 

 malian anatomy for the fish's bones. We can 



