186 P. W. GAMBLE, B.SC. 



organ, performing a double function, the Germans apply the term 

 "Keimdotterstock," and as an equivalent I shall use " germ-yolk-gland ," 

 although, strictly speaking, the word "gland" should apply to the 

 vitelline portion only. 



In the great majority of Turbellaria the two parts become separate 

 organs with distinct functions. For these I use the old terms 

 germarium for the ovarian organ, and vitellarium or yolk-gland for the 

 nutritive one. The term vagina I apply to that part of the female 

 genital duct which forms a sheath for the penis during copulation. 

 For the storage and nutrition of the spermatozoa various accessory 

 organs are developed. For a single organ, serving to retain the sperm 

 until fertilisation is accomplished, the term spermotheca is a convenient 

 equivalent for "bursa seminalis," used by v. Graff. In many cases 

 (e.g., Vorticida3) two organs are present, one of which receives the male 

 products of another individual, and then passes it on to the second, 

 from which fertilisation takes place. I retain the term bursa 

 copulatrix for the former muscular structure, and receptaculum seminis 

 for the latter. While the ova are being duly fertilised, provided with 

 food-yolk, and surrounded by an egg-capsule, they are usually retained 

 within the body of the parent during, and usually also a short time 

 after, these changes. Consequently a certain amount of development 

 is passed through. To the region in which this takes place the term 

 uterus may be applied. 



The testes offer no difficulties of terminology. Vasa efferentia may 

 be applied to cases such as Polyclads, where a fine duct passes from 

 each testis-follicle, and vasa deferentia to the paired canals formed by 

 their union. These canals usually open into a vesicula seminalis. 

 Accessory male glands are very commonly present, and possess fairly 

 uniform histological characters. Hence the terms granule-gland, 

 granule-duct, vesicula granulorum. The duct through which the male 

 products reach the exterior is the ductus ejaculatorius, and any 

 chitinous investment round it may be called a copulatory organ. 



As regards the authors' names appended to the species, I have 

 endeavoured to follow the British Association rules. Von Graff, in 

 his " Monograph,' has employed the name of that author who first 

 used the definitive combination of genus and species. Thus Vortex 

 balticus, M. S. Schultze, becomes Provortex balticus, v. Graff, whereas 

 I write it Provortex balticus (M. S. Schultze). 



