100 BULLETIN 150, UNITED STATES NATIONAL MUSEUM 



In only one species, C. longifilis, are the middle pectoral rays rudimen- 

 tary. In this species the notch extends nearly to the base of the fin. 



The length of the lower pectoral lobe varies considerably among 

 the different species but is quite constant for any one species and is 

 of considerable taxonomic importance. It apparently varies but 

 slightly with age. In C. abhreviatus the lower pectoral lobe is con- 

 tained two or more times in the head, and in C. rhodomelas and C. 

 colletti it exceeds the length of the head, and in C. longifilis is greatly 

 elongate, extending past the middle of the body. The rays of the 

 lower lobe are graduated in length and partly free. In C. colletti 

 the rays are free nearly to the base. In none of the species of the 

 genus, however, do they become as free as in some species of Parali- 

 paris. The tips of^the rays are sometimes coiled or wavy. 



The upper edge of the pectoral fin remains at about the same level 

 on the side of the body throughout the genus. 



Dislc. — The ventral disk becomes greatly modified both in size 

 and shape in this genus. Its position also changes and the measure- 

 ment "snout to disk" is of considerable importance. In the more 

 generalized species the disk is large and oval or round and in every 

 respect resembles the disk in Liparis. As we examine some of the 

 more specialized species we find the disk becoming smaller. In 

 C. gilherti it is contained seven to nine times in the head, and in C. 

 ostentum it has become minute but remains perfect in structure. 



With the reduction in size the disk becomes triangular and cupped. 

 The triangular shape is caused by the margin posteriorly and on the 

 sides anteriorly folding over the center. When the whole margin is 

 folded over the center the disk is cupped. Whether or not the tri- 

 angular shape always precedes the cupped condition is uncertain. 

 The width of the margin is greatly reduced in some species. Examples 

 of a triangular disk can be seen on C. rhodomelas and C. longipinnis and 

 of a cupped disk on C. abhreviatus, C. colletti, C. hatliycoetus , and others. 

 In C. rhodomelas the margin of the disk is very narrow. 



The above enumerated characters of the disk are of considerable tax- 

 onomic importance. The size and shape of the disk vary somewhat 

 within a species but in general they aid in distinguishing many of the 

 species. 



Vent. — The vent is typically close behind the disk and the distance 

 between the two varies little in the majority of the species. There are 

 three species in which the vent is some distance from the disk. In C. 

 attenuatus and C. pycnosoma the vent is about midway between the 

 disk and margin of the anal fin and in C. opisthotremus it is nearer the 

 anal fin than the disk. ^ 



PseudohrancMae.—Pseudohrsinchisie are absent from many if not 

 from all the species of the genus. The following species were found to 

 lack pseudobranchiae : gilherti, melanurus, cypselurus, howersianus, col- 



