NOTE ON THE CLASPERS OF HEPTANCHUS. 

 By W. A. Haswbll, M.A., B. Sc. 



Plate X. 



la most Elasmobranchii there is found at the base of the clasper 

 a cavity lined either completely (Sharks), or in a special position 

 (Rays), with gland-cells secreting a sort of sebaceous material.* 

 This cavity is excavated in the substance of the posterior lobe of 

 the pelvic fin, and, opening from it, is a groove which runs along 

 the clasper to its apex. In Heptanchus indicus, however, of which 

 I have recently had the opportunity of examiuing fresh specimens, 

 these organs present an arrangement which is in some respects 

 entirely unlike that observed in other Elasmobranchs, The 

 clasper itself has the form usual in Sharks, But the longitudinal 

 groove which runs along its dorsal border is pushed in, as it were, 

 in its proximal portion to form a deep, loose, vascular pouch of 

 skin. Proximally the gland ends blindly. Enclosing the pouch 

 and the claspers themselves is the posterior portion of the pelvic 

 fin, which has the form of a wide sheath open internally and sup- 

 ported by the posterior fin-rays. When the two sheaths of opposite 

 sides are drawn a little in towards one another they form a 

 complete covering for the organs, only the tips being exposed. 

 The inside of this sheath is lined with soft, highly vascular skin, 

 devoid of scales and apparently glandular. 



What purpose is served by this unusual arrangement it would 

 be difficult to determine in the absence of any exact information 

 as to the functions of the various parts in other forms ; but the 

 conjecture may be hazarded that the pouch serves as a reservoir 



* See K. R. Petri, Die Copulationsorgome der Plagiostomen, Zeitschr. f, 

 wiss. Zool. xxx., 2 pp. 288 — 335, pi. xvi. — xviii. 



