86 LECTURE V. 



angular processes ; the lower border of the orbit, when present, 

 projects freely downwards ; and the posterior border of the bony 

 operculum is often produced backwards in the form of spines. 



It would seem an almost hopeless task to attempt to arrange 

 naturally and determine satisfactorily the numerous bones of this 

 most complex part of the skeleton of Fishes, so as to convey as clear 

 and tenable a knowledge of them as the Anthropotomist does of the 

 human skull : we need but glance, indeed, at the labours which Com- 

 parative Anatomists of the highest merit have bestowed on the era ■ 

 niology of Fishes, in order to appreciate its difficulty, and at the same 

 time its importance. By these labours, however, of which the best 

 summary will be found in Cuvier's great work on Recent Fishes 

 (xxiii. t. i.), and in Agassiz's most valuable and original History of 

 Fossil Fishes* (xxii.), not only has the descriptive osteology of the 

 head of Fishes been rendered as complete and minute as that of the 

 human skull, but it may be truly averred to be more intelligible, 

 more philosophical, more agreeable with the natural arrangement 

 and true signification of the series of bones of which that complex 

 part of the skeleton is composed. It must be confessed that, in this 

 respect, Ichthyotomy, as true anatomical science, is at present in ad- 

 vance of Anthropotomy. 



After an attentive study of the original authors in this field of 

 Anatomy, testing their extensive series of comparisons of the per- 

 manent forms of the skull in the higher Vertebrate classes, and the 

 transitoi'y foetal conditions of each, with the results of my own ob- 

 servations, I have been led to the following view of the craniology of 

 Fishes, 



The bones of the skull are primarily divided, in Anthropotomy, 

 into those of the cranium and those of the face ; but the proportions 

 which these divisions bear to each other in Man are reversed in 

 Fishes. According to this binary classification, the facial series in 

 Fishes includes an extensive system of bones — the hyoid — of which 

 part only, viz. the ' styloid element,' is admitted into the skull by 

 the Anthropotomist, who describes it as a process of the ' temporal 

 bone,' Tliis very ' temporal,' moreover, is originally and essentially 

 an assemblage of bones, which are always distinct in Fishes and 

 Reptiles; and the squamous part, which enters so largely into the 



* The general results of the study of the skull of Fishes are briefly but clearly 

 given in the recent compendiums of Comparative Anatomy, by Dr. Cams (xxxiv.), 

 Prof. Grant (xxviii. ), Prof. Rymer Jones (xxix. ), and Dr. Kostlin (xxxv. ). The 

 generally accepted views of the classification and homologies of the cranial bones 

 are those adopted in the very useful " Elements of the Comparative Anatomy of the 

 Vertebrate Animals," by the learned Gottingen Professor (Wagner), ably translated 

 by Mr. Tulk (Longmans, 8vo. 1845). 



