210 



ICHTHYOLOGY. 



Introduc- ftirnished with a stout bony spine at the front of the dor- are remarkable among bony fishes for these dermal wea- introduc- 



''""■ sal fin; and the Sticklebacks (fig. 13) have curious sculp- pons. tion. 



Osteology. . ^ ^ _ _ Osteology. 





Fij. 13. 

 Qasterosteits insculptus, discovered by Sir Edward Belcher in the high lati- 

 tude of 7;°, at tlie northern outlet of Wellington Sound, when in searcli of 

 Sir John Franklin. 



tared bony spines in the ventrals as well as in the dorsals. 

 In most Siluridce the pectorals are supported by a strong 

 and dangerous spine. Many of the rays have detached 

 serrated spines on the upper part of the tail ; and in palae- 

 ontology similar spines, named " Ichthyodorulites," are 

 the sole indications remaining of the plagiostomes of for- 





^, 



Fig. 14. 

 Monoccntris Japonica. 



mer epochs. The Siluroids and Trigger-fish {Balistes) 



Fie. 15. 

 Skeleton of a Perch's Head. 



That the skull' (fig. 15) consists of a series of four vertebra; 

 modified for containing the cerebral enlargement of the 

 anterior end of the nervous column, has been most fully 

 demonstrated by Professor Owen. Each is divided into a 

 neural arch with which the centrum and parapophyses are 

 more immediately connected, and a hcemal arch with its 

 appendages. 



A. Beginning next the trunk, the following are the 

 names of the neural arches in the order of their succession : 

 — I. Epencephalic arch. II. Mesencephalic arch. III. 

 Prosencephalic arch. IV. Rhinencephalic arch. 



A A. The haemal arches are, — 1. Scapular or scapulo-cora- 

 coid. 2. Hyoid or stylo-hyoid. 3. Mandibular or tympano- 

 mandibular. 4. Maxillary or palato-maxillary. The appen- 

 dages of the haemal arches are, — \st. The pectoral. 2rf, 

 The branchiostegal. 3t/, The opercular. 4</«, The pterygoid. 



• For the sake of more clearly exhibiting the relations of the different members of the osteological system, and to furnish a key to 

 figures, we here subjoin a Table of the names of the parts of the skeleton as fi.xed by Owen, with Cuvier's synonyms. 



c. denotes ccntrtim; n. neurapophysis ; s. spine; ^3.r. parapophysis ; ^\. pleurapophysis ; h. hcemapophysis ; hs. hcemal spine ; d. diverg- 

 ing appendage. 



The numbers after the French names have reference to figures 10, 15, 20, and 21. 



ENDO-SKELETON. 



FRONTAL YEHTEBRA. 



