10 Proceedings of the Biological Society of Washington. 



case in similar situations, this "lumping" of the genera, if 

 undertaken, must be extensive, for they form several more or 

 less uninterrupted series. In the following key an attempt has 

 been made to express the natural arrangement of genera form- 

 ing these series; to compare directly the types most closely 

 related; and to emphasize the isolated position of the more 

 aberrant species. Detailed descriptions of the genera and species 

 with notes on distribution, etc., are given by Jordan and Ever- 

 mann (Bull. U. S. Nat. Mus., 47, 2, 1898, pp. 1493-1511), and 

 need not be repeated. 



ANALYTICAL KEY TO THE GENERA AND SPECIES OF THE 



EMBIOTOCIDAE.* 



A 1 . — Anal fin of the male with the same number of fin-rays as that of 

 the female ; no oval depression near its base ; front of fin enlarged 

 and fleshy ; this fleshy portion modified posteriorly into a hard ex- 

 crescence, followed by a large and prominent, oval, gland-like structure 

 opening anteriorly, the form of which is subject to some variation in 

 the different genera; anal rays variously crowded or elongate in cer- 

 tain areas, none of them enlarged to form a triangular plate. Teeth 



of the jaws bluntly conic, uniserial Embiotocinae. 



a 1 . — "Spinous dorsal longer than the soft part, of 16 to 18 spines; 

 second anal spine the largest ' ' ; scales large ; lower pharyngeal flat ; 

 "vertebrae 14+20=34"; abdomen short; outline of spinous dor- 

 sal rounded; body robust; caudal fin lunate; lower lip without 

 frenum; gill-rakers short . ... . . Hysterocarpus traski Gibbons. t 



a 2 . — Spinous dorsal shorter than the soft part; of 8 to 11 spines; 

 anal spines graduated. 



ft 1 . — Scales rather small, more than 55 in the lateral line. 

 c 1 . — " Dentigerous surface of lower pharyngeals flat or con- 

 cave" ; dorsal soft rays not abruptly higher than the spines. 

 d 1 . — Outline of spinous dorsal rounded; the spines stronger; 

 body robust; the caudal peduncle deep ; caudal fin lunate. 

 e 1 . — Abdominal vertebrae 14 or 15; abdomen shorter, the 

 anus being located well before middle of body, excluding 

 the head and the caudal fin ; anal fin with a longer base. 

 y 1 . — "Lower lip without a frenum, very thick, lobed or 

 incised behind; gill-rakers long: vertebrae 14 + 22= 

 36 " ; snout blunter and more massive, even in the 

 embryo Rhacochilus toxotes Agassiz. 



* These portions of the descriptions in quotation marks are extracted from the key 

 used by Jordan and Evermann (Bull. U. S. Nat. Mus., 47. 2, 1898, pp. 1494-1495). All of 

 the species have been reexamined by the writer, and nearly all of the characters men- 

 tioned are confirmed, or used now for the first time. 



+ The fresh-water species ; regarded by Jordan and Evermann, and others, as typical 

 of a distinct subfamily, but its relationships with the Embiotocinae (as here outlined) 

 are very close. 



