914 



SCIENCE. 



I.N. S. Vol. III. No. 78. 



SO called is by no means identical with the 

 Teleosts, as stated (pp. 8, 165). The 

 Teleocephali are an order of the sub-class 

 of Teleosts restricted to such as have tj'pic- 

 ally complete intermaxillary and maxillary 

 bones and cranial in number exemplified 

 or closely approximated by the Perch ; it 

 thus contrasts with the Nematognathi, the 

 Apodes, and others. 



The ISTematognaths are considered by Dr. 

 Dean, as by most old authors, to be ' closely 

 akin to the Sturgeon' (p. 147J, and, indeed, 

 it is claimed that the Catfish ' is, perhaps, a 

 direct descendant of some early type of 

 Mesozoic Palseoniscoid' (p. 171). The 

 same idea is also expressed in the exhibit 

 of ' the phylogeny of the Teleostomes ' (p. 

 166), where the ' Siluroid ' branch is inter- 

 posed between the ' Sturgeon ' and ' Amia ' 

 and well separated from the ' Physostome.' 

 It is likewise declared that ' their armour- 

 ing is metameral and archaic, their sensory 

 canals primitive in structure and arrange- 

 ment ' (p. 172). All this maybe quite in 

 accord with what has been believed by the 

 most learned ichthyologists of old, but can 

 be now known to be baseless. The Silu- 

 i-oids have no direct relations with the 

 Sturgeons, the Coccosteids, or any of the 

 extinct ganoid fishes, and are undoubtedly 

 derivatives from the same stock as the 

 Characinids and the Cyprinids. The arma- 

 ture, instead of being archaic, is of secon- 

 dary development. The fishes themselves 

 are more specialized and therefore more 

 distant from the Ganoids than the Characi- 

 nids and various other forms. The entire 

 structure, including brain, vascular system, 

 skeleton, weberian ossicles, air bladder, 

 and morphological development generally, 

 proves this and in turn is illustrated by this 

 conception of their relationship. The sim- 

 ilarity in appearance of Loricariids and 

 Acipenserids, great as it is, is entirelj' super- 

 ficial and illusive and should no longer be 

 allowed to mislead. While referring to 



the Siluroids, it may be added that there is 

 more than a 'single European species, Silurus 

 (jlanis ' (p. 171). There is another concern- 

 ing which many data were published over 

 2200 years ago — the true Glanis of the 

 Greeks and of Aristotle especially, the 

 Silurus, or Parasihirus Aristotelis. Although 

 this Greek fish has generally been supposed 

 to be identical with ' the gigantic Wels of 

 of the Danube,' it was, as declared by 

 Agassiz 40 years ago, and demonstrated 

 lately by Mr. Garman, a very different 

 species. 



Dr. Dean's misconceptions respecting the 

 Siluroids are those of others. He declines to 

 go to the extremes of some others, and very 

 properly notes (p. 61) disbelief in the 'cir- 

 rhostomial origin [ascribed] to the mouth 

 parts of a Teleostome (catfish).' 



Some of the statements as to distribution 

 and extent of groups may mislead. Of the 

 Mormyrids, or genus Mormyrus as Dr. 

 Dean calls the group, it is said, ' its species 

 are restricted to the Mle ' (p. 172), whereas 

 species occur in all the rivers of tropical 

 Africa. Of the Anacanthini, it is claimed 

 'that as many, perhaps, as one-quarter of the 

 existing genera of fishes may be assigned to 

 this type ' (p. 171) : in fact, the Anacanthmi 

 are comparatively few in number, especi- 

 ally if properly restricted. It is also said 

 that ' of existing fishes about one-half are 

 essentiallj' percoid ' (p. 171) and this also 

 is a very much exaggerated statement. 



The care which Dr. Dean has taken to 

 bring his work up to date has already been 

 adverted to in connection with Semon's re- 

 searches on the embryology of Neoceratodus. 

 Another example is found in the incorpo- 

 ration of the latest news about the earliest 

 ' cyclostome.' References to recent memoirs 

 (1890-92) on that interesting form are given 

 (p. 238), and an illustration is reproduced 

 (p. 65). We can scarcely agree with Dr. 

 Dean, however, that it ' seems undoubtedly 

 a lamprey;' apparently it represents not 



