FLOrXDERS OF GENUS PARALICHTHYS AXD RELATED GENERA 



319 



mouth, smaller teeth, ctenoitl s<'ales, ami other 

 salient differences. Some difficulty may be en- 

 countered in properly distinguishing scattered 

 specimens of this species from alhlgutta or htho- 

 stigmu wliere theii- ranges overlap. Doubtful 

 specimens of dentatua in these localities may gen- 

 erally be properly placed by the more numerous 

 gill rakers. For separating the residual few speci- 

 mens in which the number of gill rakers approach 

 the other two species see page 282. The three spe- 

 cies ai'e evidently quite closely related. 



Bionomics 



Spaipning 'period. — The spawning period of 

 this species is evidently the late fall and winter 

 possibly extending to early spring in Chesapeake 

 Bay. judging by available evidence. Hildebrand 

 and Schroeder (1928 : 166) found specimens taken 

 in Chesapeake Bay during October, having com- 

 paratively large gonads. Hildebrand (op. cit.) 

 found the gonads of fish taken at Beaufort, N. C, 

 to be partly developed during fall and early win- 

 ter while those taken in March and Api'il were 

 fully si)ent. Abundant data on the size of the 

 fry and its bearing on the spawning season of the 

 species is furnished by Hildel)rand and Cable 

 (1930: 470).^ In the very extensive collections 

 made at Beaufort. N. C. and reported on by these 

 investigators, individuals 25 mm. (1 inch) or less 

 in length were taken from September to May, the 

 bulk of the specimens having been collected in 

 November and December. As three common 

 species occur at Beaufort, N. C, and no characters 

 for separating the very young fry, before the 

 fin rays and gill rakers become differentiated, are 

 known at present, only the approximate spawning 

 period for the separate species may be surmised. 

 It is possible that the height of spawning varies 

 with the different species. If that is the case, the 

 spawning periods of the separate species probably 

 overlap to a large extent, since the data published 

 by Hildebrand ami Cable do not show anv domi- 



" The most extensive studies on the biology of ParnXirhthys 

 wlilili have been earried out so far, are those by Hllileliraml and 

 Cable to whose report tlie nailer is referred for detailed accounts. 

 These authors made their studies at Beaufort, N. C. Since, 

 however, three clos<'ly related species of Pninlirhtlnis, are loni- 

 mon tliere, and it is dllliiult or impossible to separate the fry 

 by s|)ecies, Heaufort is not a favorable place to stud.v the develop- 

 ment of di'iilnliiK. The Chesapeake Bay region and localities 

 farther north are more suitable because only this one species 

 of Paralichthys occurs there. 



nant concentration of fry at different periods of 

 time, when grouped by month intervals. (Per- 

 haps, in a grouping of data by smaller intervals 

 of lime differing heights of spawning would show 

 up to some extent.) In Chesapeake Bay spawn- 

 ing apparentlj' takes place later, in the late winter 

 or earlj' spring, if we are to judge by the size of 

 the fry in relation to the season of the year when 

 taken. Thus, Hildebiand and Schroeder (op. cit.) 

 report fry taken there in May and June to be ap- 

 proximatel}' 25 mm. (0.9 to 1.1 inches). During 

 1892 the Grampun made some collections in Chesa- 

 peake Bay of young PaniHrliflnjs di-nfatus which 

 are now preserved in the National Museum as fol- 

 lows: June 28, 3 specimens, 49, 58 and 83 mm.; 

 June 29, 1 specimen, 40 mm. ; July 4, 2 specimens, 

 .38 and 50 mm. : July 6, 2 specimens, 42 and 

 45 mm. ; July 16, 1 specimen, 57 mm. A compari- 

 son of the measurements of these few specimens 

 with the extensive data given by Hildebrand and 

 Cable seems to indicate that sjjuwning occurs 

 somewhat later in Chesapeake Bay. 



Spaii'iihig places a7id distribution of ft-y. — In 

 regard to particulai' situations where spawning 

 takes place, Bigelow and Welsh (1925: 494) 

 and Hildebrand and Schroeder (1928: 1G6) sug- 

 gest the possibility of the fish going to deep water 

 to spawn. There is evidence showing a general 

 migration of the fish to deejier water with the 

 advent of cold weather (p. 320). One of the ob- 

 jects of this migration may be spawning. That 

 spawning takes place offshore is further indicated 

 by the distribution of the fry as found by Hilde- 

 brand and Cable (1930: 474). Fry up to 3 mm. 

 were taken only at sea; somewhat larger ones, up 

 to 5 mm., were taken also within Beaufort Harbor. 

 but they were much more numerous outside Beau- 

 fort inlet: while sjiecimens 6 to 10 mm. are about 

 equally distributed in the inner and outer waters, 

 extending from 12 to 15 miles offshore into the 

 estuaries of Newport and North Rivers. This 

 furnishes evidence of a gradual movement of the 

 fry to the inner waters from offshoie where they 

 hatch. 



The type of eggs is unknown at ])resent. l)ut il 

 is probably demersal, as recently hatched ivy were 

 taken by Hildebrand and Cable (1930: 475) 

 chiefly on the bottom. If they hatch on the bot- 



