AUTHOR'S ABSTRACT OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, JUNE 21 
THE COMPARATIVE MORPHOLOGY OF THE 
SECONDARY SEXUAL CHARACTERS OF 
ELASMOBRANCH FISHES 
THE CLASPERS, CLASPER SIPHONS, AND CLASPER GLANDS 
MEMOIR I 
W. HAROLD LEIGH-SHARPE, M. Sc. (Lonp.) 
TWELVE TEXT FIGURES! 
The present memoir deals with the following species: 
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SHEN AU SET CPUEOTU Ea een ee mS Rn Re, Ae, Poe ee 252 
PAWS OUE GLIAL BVM ERTS yey chi a) See hte < OAC. a: facekole isha nl v1.65, se iaie os 616 259 
VATA ECIRCUATI Samer 2 melee tate cas teh <A aee A aS cco teeter. 260 
In the male elasmobranchs, where fertilization is internal, 
the basal element of each pelvic fin (basipterygium) is prolonged 
to form a stout backwardly directed skeletal rod supporting a 
portion of the fin which is demarcated from the remainder and 
specially modified to form a copulatory organ, the clasper. 
The clasper is rolled up in a manner resembling a scroll, so 
that instead of being a groove, as it is usually described, it is a 
sufficiently closed tube along the greater portion of its middle 
length, though the edges may not be and usually are not com- 
pletely fused, but overlapping. This tube is one along which 
spermatozoa pass, injected by an apparatus, the siphon, which 
has not hitherto been sufficiently well known and investigated. 
The anterior proximal opening into this scroll-like clasper 
groove or tube will be hereafter known for the sake of brevity 
as the apopyle, the posterior, distal exit:from the same as the 
hypopyle. In the sharks and dogfish the apopyle is close to 
1 The figures were executed by Miss E. C. Humphreys from the author’s dis- 
sections and preparations, except figure 4 by Michael G. L. Perkins, to both of 
whom best thanks are tendered. 
245 
