MORPHOLOGY OF CYPRINODONT FISHES. O 



further back it increases in size and is well-defined ; owing to a 

 strong constriction of ttie body just behind its attachment, the 

 posterior part of the priapium projects but little beyond the 

 general outline of the abdominal region. 



On one side, the proctal side, which may be either right or 

 left, may be seen the anus (a.) ; above and behind it can be seen 

 the outline of the enlarged terminal coil of the vas deferens (v.d.), 

 occupying most of the free posterior part of the priapium, which 

 ends in a membranous fringe, produced into some half-dozen 

 slender processes. On the proctal side a shallow groove marks 

 the boundary between the priapium and the body of the fish, but 

 -on the ether side, the aproctal side, there is a much deeper groove, 

 margined above by a thick fold of the integument ; this gi'oove is 

 lined by a glandular epidermis, and may be termed the glandular 

 groove (g.). Posteriorly a dermal fold arises from the inner wall 

 of the groove, and this fold is continued backwards on the fi'ee 

 part of the priapium as the roof of another groove, leading from 

 the glandular groove to the end of the priapium ; this may be 

 termed the efferent groove (ef.). 



The enlai'ged part of the vas deferens lies below the floor of the 

 ■efferent groove ; here it is running backwards, and at the end of 

 the priapium it curves round from the proctal to the aproctal side 

 and then runs upwards and forwards, ending in a seminal papilla 

 (sp.), which opens into the glandular groove, the terminal aper- 

 ture being a wide slit. Directly in front of the seminal papilla 

 is a papilliform projection {2J-), which may be termed the infra- 

 sulcar prominence. Below the infrasulcar prominence is the 

 articulation of the ctenactinium (ct.), a long and slender movable 

 bony appendage that curves backwards and upwards, then for- 

 wards to below the eye, and, finally, downwards and across beneath 

 the chin ; a short pointed process, directed outwards and down- 

 wards, arises from its concave edge above the infrasulcar 

 prominence. 



Further forwards, a rather soft appendage, subconical in form 

 and with its apex directed backwards, lies in the glandular groove ; 

 at its base it is separated by a deep constriction from a lateral 

 mass of tissue that tapers forwards to the anterior end of the pri- 

 apium. This mass of tissue may be termed the pulvinulus (pv.) 

 and its appendage the pulvinular appendage (jyva.); a small 

 antrorse spine (s.) projects from the posterior part of the pul- 

 vinulus, and a branch of the glandular groove runs forwards 

 between the priapium proper and the lower part of the pul- 

 vinulus ; this infrapulvinular groove narrows forwards and 

 disappears a little in advance of the level of the pulvinular 

 spine. 



b. Skeleton (PI. T. B, and text-fig. 3). 



This differs from that of the female in that one of the cleithi-a, 

 the third vertebra, and the first pair of ribs are modified in 



