ON THE APPENDICES GENITALES (CLASPERS) IN THE SELACHIANS. 43 



aperture (at /') leading into a pocket between the ventral terminal piece (Tv) and the ventral 

 covering piece v. 



If the lateral lip of the appendix-slit above the terminal part is lifted, a thick glandular 

 body is seen protruding from the medial side of the canal, in which feature this species differs from 

 all other Sharks I have had the occasion to examine. This gland will he more particularly mentioned 

 afterwards. 



The skeleton. Between the basale and the appendix-stem three short pieces (b 1 , b 2 , and b.) 

 are found, each bearing one of the three hindmost rays (the two hindmost of these rays are termin- 

 ally quite coalesced for a long way). At a first glance the piece /? seems to be wanting, but a closer 

 examination shows it to be present, represented by a little cartilage, arising from the lateral hind 

 corner of b,, and joined by a particular articulation to the proximal end of the appendix-stem b. Con- 

 trary to what commonly is the case in the Sharks, the piece j) does not here articulate proximally 

 with the basale. 



The appendix-stem (b) is long, considerably longer than the basale (the ratio is 3/ 2 ), round 

 (with the exception of the proximal part where it dorso-ventrally is somewhat flattened); the style is 

 long, not, however, reaching to the hindmost point of the terminal part. The marginal cartilages are 

 short, and are only found at the distal part of b; contrary to what commonly is the case in the 

 Sharks, the ventral marginal cartilage is the one reaching most forward. The general shape of 

 these cartilages, I think, may be seen with sufficient clearness from the figures. The ventral marginal 

 cartilage bends towards the dorsal one with a plate similar to that found in many other Sharks, but 

 does not cpiite reach it. But this plate is here in a peculiar way hollow, being behind split into two 

 lamella? receiving between themselves the proximal end of the piece Tv; this piece, then, projects into 

 the ventral cartilage, quite covered, until the point marked * in fig. 25 : ). The hindmost end of the 

 inner one of these two lamellae protruding very much, the appendix-slit is by its transition to the 

 terminal part straightened to an extraordinarily narrow passage. 



The number of terminal pieces must in reality be taken to be four; but to these four is 

 added a good-sized, ventrally situated piece, v, rounded in a scutiform manner, and partly covering 

 the terminal part (see fig. 24) behind the ventral marginal cartilage. This piece has developed in the 

 aponeurosis which, in the Sharks hitherto mentioned, encloses the terminal part, and it serves like 

 this aponeurosis for inserting the large AIusc. dilatator. If this piece v is removed, the ordinary ter- 

 minal pieces are easily recognized: Td which is rather broad, flat, with a thickened edge medially 

 (which edge follows the style closely, but reaches a little further backward), and a sharp and thin 

 edge laterally; Td, proximally joined to the foregoing piece, is a broad, but thin, and but slightly 

 calcified lamella. Tv is of a very peculiar shape, thick and solid, ventrally rounded, dorsally, towards 

 the slit, deeply hollowed in a spoon-like shape ; its proximal end, as already mentioned, passes its arti- 

 culation with Rv, and enters between the two lamelke of the overlapping plate; with the proximal 

 end articulates, completely hidden, a little calcified piece representing the thorn or spur , 7^,; this 

 latter piece (see fig. 27) is proximally irregularly head-shaped, and from this thick part a thinner one 



i) If in Acanlhias or Spinax the projection of the ventral marginal cartilage, mentioned at p. 2S, was more developed, 

 and proximally prolonged, a similar state of matters might be the result. 



6* 



