290 THE ELASMOBRANCH FISHES 



Genital System 



The genital system in Heptanchus is of an interesting type. Each ovary {ov., 

 fig. 252) of the adnlt female is large and is located in the anterior part of the 

 body cavity where it is suspended by a mesentery, the mesovarium. It con- 

 tains numerous ova which can be seen through the thin wall. From the main 

 mass of the ovary there is a posterior continuation of tissue which is devoid 

 of ova. This is possibly the rudiment of an epigonal organ (epg.) found in 

 some of the other Elasmobranchs. 



A singular condition is found in Heptanchus, similar to that described by 

 Semper (1875) for Hexanchns, in which a rudimentary testis is associated 

 with the ovary. In Heptanchus maculatus this testis {t., fig. 252) lies in the 

 mesovariimi at the base of the ovary and runs parallel with it. It consists of an 

 anterior larger part and a marked ridge or swelling which extends posteriorly 

 practically the entire length of the ovary. It will be noted that the posterior 

 extent of this rudimentary testis is about the same as that of the coil in the 

 "Wolffian duct previously described. 



Unconnected with the ovaries are the tubes or oviducts {ocl.) through which 

 the ova reach the exterior. Right and left oviducts are reached from the body 

 cavity by a common opening or wide funnel (^., figs. 251a and 252) located 

 just ventral to the base of the liver. The oviducts pass outward from the fun- 

 nel and then inward to the anterior margin of the mesovarium where they en- 

 large to form the shell gland (s.g.). Posterior to the shell gland the oviduct 

 passes ventral to the Wolffian duct as a tube of considerable size, but it is not 

 so greatly enlarged in Heptanchus as in many other Elasmobranchs in which 

 it forms the conspicuous uterus (see fig. 253a, Squalus sucMii). At their 

 termini the two oviducts enter the cloaca separately and not in common with 

 ureters or Wolffian dvicts, that is, not through the urinaiy papilla. 



The genital glands of the male are the paired testes which like the ovaries of 

 the female occupy an anterior position in the body cavity. In figure 251b of 

 the immature specimen the testis (t.) appears as a long mass of tissue. Only 

 the anterior part of this, however, is functional. The posterior part represents 

 the rudimentary epigonal organ like that in the female. The testis is swung 

 from the body wall by a mesentery, the mesorchium, which is comparable to 

 the mesovarium suspending the ovary. 



Running along the median and anterior part of the testis is the central canal 

 (c.c.) , which is put into communication with the vas deferens (Wolffian duct) 

 by vasa eflferentia (v.e.), six of which are present in Heptanchus. The vasa 

 efferentia are derived from funnels, present on the mesorchium. We shall de- 

 scribe this system more completely in the general part, but here attention may 

 be directed to it briefly. The general plan of these tubes may be made out in 

 figure 254a {nph.) where several of them open on the mesorectum which sus- 

 pends the rectal gland. These openings are the nephrostomes, the tubes of 

 which pass out toward the kidney tissue. In the region of the testis the mouths 



