ENTOZOA. 93 



drical bodies, which of themselves occupy almost the whole cavity of 

 testes is characterised by the numerous actively moving capillary 

 spermatozoa. The yellowish wax-like cement which is often found 

 sticking round the vulva of the female is probably the secretion of the 

 accessory pyriform bodies. The male echinorhyncus is generally half 

 the body, extending from the proboscis to the tail, and appearing to 

 float freely in the fluid of the general cavity: they contain a granulo- 

 cellular mass in which the ova are developed. When ripe, the ovaria 

 dehisce and the ova fall into the cavity of the body. The oviduct is 

 supported by a suspensory ligament answering to that in the male, 

 and opens freely, like the fallopian tube, by a bell-shaped mouth, into 

 the cavity. The ova are taken up by it, and conveyed to a short mus- 

 cular uterus, and are excluded by a vulva at the liinder end of the 

 body. When first liberated, the ova have a single tunic, and consist 

 of the vitellus in a minutely granular, and sometimes vesicular mass, 

 but without a trace of germinal vesicle. In the uterus the ova have 

 acquired two additional coats. 



LECTUEE YI. 



ENTOZOA. 



The four orders of the class Entozoa which have already been 

 described, are less natural than the order Nematoiclea, w^hich will 

 chiefly occupy our attention in the present lecture. The Cystica, 

 Cestoidea, Trematoda, and Acanthocephala, are far from being re- 

 spectively equivalent to the order Netnatoidea, either as regards 

 grade, difference, or circumscription of organic characters. The 

 transition from the cystic to the ta^nioid Entozoa was so obvious and 

 close, by the Cysticercus fasciolaris, for example, that they were 

 combined in the snme order '•'■ Tceinoidea^'' in the " Regne Animal." 

 Cuvier, however, did not abolish the order Cestoidea, but separated 

 the jointless Ligidce^ in wliich the head has neither suckers, bothria, 

 nor uncinated proboscis, from the other Taanioids, in order to form it. 

 It is hardly possible, however, to separate from the Tsenioids of 

 Cuvier, the intestinal Ligidm of water-fowl, in which traces of both 

 bothria and generative organs begin to manifest themselves. And 

 Rudolphi's hypothesis that such Ligulce might be the more simple 

 Ligulce of fishes that had been transferred to the warmer intestines of 

 the birds preying upon such fishes, there to undergo their final meta- 

 morphoses, has been established by later observations, which have 

 also shown that the Cystica of Rudolphi are for the most part, if not 

 all, larval forms, in a normal or abnormal state, of the Cestoidea. 

 With respect to the higher organised Cestoidea of Rudolphi, it has 



