182 Mr. C. T. Regan on the Osteology and 



ueakly ossified ; tliere are 48 to 50 vertebrse. The pectoral 

 fin skeleton is as in generalized Cottidse ; the pelvic fins are 

 absent. Two species of Comephoriis are known from the 

 depths of Lake Baikal ; a very good account of the structure 

 has been given by Berg (' Die Oataphracti des Baikal-See,' 

 1907). 



Family 5. Agonidae. 



The Agonidae are extremely closely related to the Cottidae, 

 diflfering from them only in the complete investment of bony 

 plates. The pectoral arch is of the most generalized Cottid 

 type, witii the coracoids very narrowly separated by cartilage. 

 In most of the genera the suborbitals are arranged as in the 

 Cottidse, but in Agonus and related genera they completely 

 cover the cheek and approximate to those of the Triglidse in 

 form and position. 



Famil}^ 6. Cyclopteridae. 



Differ from the Cottidse externally in that tlie 6-rayed 

 pelvic fins form a circular suctorial disc ; the rays are de- 

 pressed outwards and their bases are contiguous in the middle 

 line. The skull is depressed, the alisphenoids are absent, 

 and the parasphenoid does not extend upwards in front of 

 the prootic. All four pectoral radials are inserted on the 

 cleithrum between the widely separated hypercoracoid and 

 hypocoracoid. 



In the Cyclopterinse the form is deep, ovate, the spinous 

 dorsal is separate or absent, the soft dorsal and anal are 

 rather short and free from the caudal. The vertebras number 

 29 (10 + 19) in Cyclopterus lumpus^ the praecaudals without 

 parapophyses. The second suborbital is broad and connected 

 with the inner ridge of the prseoperculum. 



In the Liparidinje the tail is long and tapering and the 

 vertical fins are confluent. The vertebrae number -10 (10 + 30) 

 in Liparis montagui, probably more in the other genera ; 

 the prsecaudals have haemal arches from the fourth. The 

 process of the second suborbital is slender and connected 

 with the outer margin of the prseoperculum. 



Gill has given a good account of the characters of this 

 family, with figures of the skull and pectoral arch (Proc. 

 U.S. Nat. Mus. xiii. 1891, pp. 361-376). 



Suborder 2. Gasteosteoidea. 



The characters of most importance that distinguish this 

 suborder from the preceding are the subabdominal position of 



