234 PROCEEDINGS OF THE ACADEMY OP 



1st. The special form. 2d. The extension of the facial bones. 3d. The 

 armature of the lateral line. 4th. Extent of spinigerous dorsal surface. 



When it is remembered how important and how peculiar are many of the 

 characters thus enumerated, no one will hesitate to admit the close affinity 

 of the two families. The tendency will be doubtless rather to unite the two, 

 but after reflecting on the importance of the coincidence between the develop- 

 ment of the facial bones and the number of branchiostegal rays, I would 

 be very unwilling to do so myself. 



With regard to the affinities of Centriscus and Amplusile* I have consider- 

 able doubt. If, on the one hand, an affinity to the Aulostomatous fishes is 

 indicated by the development of the facial bones, the anchylosis of the an- 

 terior vertebrae, the development of the ventral fins, and, in the Amphisi- 

 loids, of the forearm ; on the other hand, by the reduced number of the 

 vertebra and some other peculiarities, they evince at least a singular analogy 

 to the Plectognaths. 



Genus Aulichthys, Brevoort. 



Body moderately elongated and almost cylindrical ; the tail from the anus 

 to the caudal fin is mush elongated and gradually merges into the very slender 

 caudal peduncle ; the latter is little depressed, but its dorsal and inferior sur- 

 faces are nearly plane. Anus subcentral. Skin mostly naked ; the lateral 

 line is protected by a row of nearly concealed plates, which are each sur- 

 mounted by a longitudinal carina ending in a spine directed backwards. Head 

 oblong and quadrangular behind the eyes, and corrugated above. Tube 

 slightly longer than the rest of the head, rigid and inflexible, tapering to the 

 front, and subquadrate. Mouth terminal and small. The intermaxillary 

 bones have moderate diverging limbs and the posterior processes longer than 

 the limbs. Teeth on the jaws very fine. Nostrils nearly simple, situated at 

 about a third of the distance from the eyes to the end of the tube. Branchi- 

 ostegal rays four on each side. Dorsal and anal fins nearly intermediate 

 between the head and caudal ; they are opposite to each other, oblong, and 

 have bifurcated rays. Anal fin close behind the anus. Dorsal spines extend- 

 ing from the nape to the fin ; they are extremely short, subtriangular and 

 compressed from before backwards, and each one is depressible in a groove, 

 intervening between which and the succeeding spine are small corrugated 

 plates. Caudal fin small or moderate. Pectoral fins oblong, with the rays 



* Ampkisile and Certtrincvs appear lo represent two distinct but allied groups, distin- 

 guished by the difference of form as well as the difference in lhe development of ihe 

 radial and ulnar bones. Centriscus velitariz Pallas, is an intermediate form. 



The Amphisilinre would then have two genera: 



1st. Amphisile Klein. Posterior process of dorsal cuirass with a spine articulated to 

 its summit. Ribs 10-11. B 4. V. 4. 



A. punctulata Brev. A. strigata Gl/ir. 



2d Arevliachme Gill. Posterior process of dorsal cuirass acute and not spinigerous. 

 Rib^ 6. B. 3. V. 3. 



Amphisile scutata Cur. 



The Orthichthyinai with one genus : 



Orlhiehlhys Gill, with a straight body and longer anal. 



Centriscus velitaris Pallas. 



The Centriscina? are represented by two genera : 



1st. Centriscops Gill. Body abruptly constricted behind the vertical fins. Breast 

 with three longitudinal rows of plates. 



Centriscus humerosus Rich. 



2d. Centriscus L. Body oblong, slowly merging into the caudal peduncle. Breast 

 with three longitudinal rows of plates. 



1. Centriscus scolopax L. 2. C. gracilis Lowe. 3. C. Japonicus Gthr. 



[April. 



