REVISION OF THE FISH FAMILY LIPARIDAE 19 



by a single elongate ray which is connected for about half its length 

 to the dorsal and anal. It is thus seen that the change in number 

 of the caudal rays is opposite to that in the dorsal and anal. 



The caudal is the most powerful in the shallow-water forms. The 

 rays are stout in these forms but become very slender and sometimes 

 wavy at the tip in the deep-sea species. The fin is typically truncate 

 or slightly rounded. It is never acuminate as has been described. In 

 Careprodus cypselurus and related species it is forked. 



Pectoral fin. — The process of specialization in the pectoral, as in the 

 caudal, includes the reduction of the number of rays. The number 

 ranges from 42 in Liparis to 21 in Careprodus and 14 in Paraliparis. 

 In contrast to the trend of modification in the family the change in 

 Liparis is to increase the number in the deep-water species. In 

 this genus the pectoral typically has more rays than the anal, while 

 in the other genera it has less. 



The outer margin of the pectoral is typically notched. This 

 notch is usually shallow but may extend to the girdle from which 

 the intermediate rays appear to have been lost. The notch is not 

 present in certain species of Liparis, Careprodus, Acantholiparis, and 

 Paraliparis. 



In Liparis the rays are nearly equally spaced on the girdle, those at 

 the notch being little more widely spaced than those above or below. 

 The separation of these rays reaches its greatest extent in Parali- 

 paris. Here also we find a resemblance to the primitive condition, 

 for P.fimhriatus has the rays evenly spaced on the girdle. 



The lower margin of the lower pectoral lobe in Liparis and Care- 

 produs consists of a series of rays regularly graduated in length. The 

 number of rays in the lower lobe of the pectoral in Paraliparis is 

 reduced and the lobe shaped as though the short anterior rays have 

 been lost. The lower lobe also becomes elongate, the rays sometimes 

 separated to the base and coiled at the tip. The greatest elongation 

 of the pectoral, however, is found in the Careprodus longifilis in 

 which species it is fully half the length of the bodj^. In other species of 

 Careprodus, as in C. colletti, the lower lobe is longer than the head. 

 In some species the length of the lower lobe increases with age. 



The upper edge of the pectoral in Cydogaster is on a level with the 

 eye, and the symphj^sis is on the lower surface of the head behind 

 the eye. In some species of Paraliparis the pectoral is lowered and as- 

 sumes a more horizontal position. The extreme is found in P. mento, 

 in which the upper edge ef tho pectoral is below the angle of the mouth 

 and the symphysis is far forward on the chin in front of the eye. 



The greatest reduction of the pectoral occurs in Nedoliparis, a 

 pelagic genus, in which the two lobes are separated and greatly 

 reduced. It probably has no function except that of balancing. An 

 extremely delicate type of fin not seen by the writer has been 



