31 



297 



dermal skeleton pass out the tendons 

 segment is a small roundish cartilage, 



left by the interspinous expansions and the 

 of the fin-muscles to the rays. The distal 

 embraced by the cleft base of the fin-ray; it articulates with two neighbouring in- 

 terneurals, and the whole series of these small cartilages is bound together by a 

 ligament. The groups of interspinous bones attached to each vertebra are more 

 or less fan-shaped; the median or the two median bones are generally straight, 

 the anterior and posterior somewhat curved at their upper ends. The whole series 

 produces a curious aspect, quite unique among teleosts. 



It appears that in the larva the arrangement of these parts is more like that 

 usually found in fishes, and is altered during growth. In larvæ from the brood- 

 pouch the spinous processes of these vertebræ are only represented by the median 

 rib just over the transverse process, and the cartilaginous interneurals are almost 

 parallel between two simple spines. 



The interneurals of the anal fin are proximally fused into one piece 

 (PI. IV, fig. 11); distally there are two branches each provided with similar expan- 

 sions as the dorsal interneurals; the expansions are joined to the two anterior 

 plates of the inferior lateral row; these plates lie in continuation of the middle- 

 lateral plates of the trunk. As in the dorsal fin the tendons for the anal fin 

 muscles pass through the narrow openings left by the internerneurals and dermal 

 armour. The two confluent interneurals are connected through muscles with the 

 lower face of the transverse processes from the foremost caudal vertebra; in spe- 

 cimens in which this vertebra has an inferior arch developed, the anal interneural 

 is situated in front of the latter. The muscles constitute a narrow, fairly long and 

 powerful bundle, which is easily separated into three, one for each fin-ray; to the 

 inner side of this bundle are found the short and weak muscles originating from 

 the interneurals. Outside the distal ends of the anal interneurals three small car- 

 tilages are found each embraced by its fin-ray; thus these interspinous bones are also 

 bisegmented. 



The fin-rays of the dorsal and anal fins are unjointed, and unbranched, 

 like those of the pectoral fins; the rays of the caudal fin are all jointed, but 

 unbranched; there are no short rays at the upper and lower margins of the cau- 

 dal fin. 



The number of rays is: D: 34—37; A: 3; C: 10. 



Cranial skeleton. As in the other members of the group under examina- 

 tion the anterior part of the skull is highly elongated, Pl.V, figs. 1—4. The nuchal 

 face as in Aiilostoma and Fistularia slopes backwards so that the bones circum- 

 scribing the occipital foramen are visible from above. On the upper aspect (fig. 1) 

 are seen: the supraoccipital (so), epiotics (ep), posttemporals (pt), pterotics (sq), 

 frontals (fr), postfrontals (pf), prefrontals (prf), meselhmoid (mes) and vomer (vo). 

 Along the middle of the last two bones a narrow, sharp crest is present. In front 

 of the slightly expanded snout-end of the vomer is found a small cartilage, con- 

 nected with the premaxilla and maxilla. The cartilage is a remnant of the contin- 



