384 



PROF. W. J. DAKIN ON THE 



however, as the ovarian tubes are concerned, I have been able to 

 distinguish peritoneal investment, tunica muscularis, and germinal 

 epithelium, and the thickness of the wall increases as we pass to 

 the infundibulum (PI. Y. fig. 24). I should be inclined, on the 

 whole, to doubt the possibility of the ovarian tubes not being 

 strictly homologous structures throughout the genus — a suggestion 

 of Willey's. 



The receptacula seminis (PI. Y. fig. 22, .Rec.Sem.) are two 

 thin -walled bags, each of which communicates with the infun- 

 dibulum of its side by two short ducts. The same condition is 

 met with in other species of Peripatus where the receptaculum 

 is present. 



The preparations which I have at my disposal show that cilia 

 are present in the tubes connecting the infundibulum with the 

 receptaculum (see PI. Y. fig. 25). This is the position in which 

 cilia were first discovered in Peripatus by Gatfron (8). It must 

 be noted that these cilia are much shorter and less distinct than 

 those described eai-lier in this paper as occurring in the nephridia. 



The two uteri do not differ essentially in histological structure 

 from the infundibula. They possess a well-developed muscu- 

 lature — transverse and longitudinal fibres surrounding the 

 epithelial wall. These uteri pass forwards for a short distance 

 and then return, usually one to each side of the alimentary canal 

 (PI. I. fig. 2, XJt.). They meet posteriorly quite near the ex- 

 ternal aperture, and a median and very shoi't vagina (Ph 1. 

 fig. 2, Yag.) leads to the exterior. During the summer months 

 each uterus presents the appearance of a string of sausages. 

 This is due to the chain of developing eggs or embryos con- 

 tained within it. The eggs are of very large size indeed, and the 

 uterus is swollen considerably round each and constricted between 

 them. The West Australian examples of Peripaioicles bring their 

 reproductive organs to maturity during the winter, which is the 

 only period of feeding and activity in general. Fecundation 

 probably takes place about August to October. The species is 

 viviparous. [For further reference see notes on Spermatogenesis 

 and Reproduction in a following paper.] 



Summary of characters diagnostic of the West Australian 

 Peripatoides. 



There are two West Australian varieties of Peripatus — sub- 

 gen. Peripatoides. They agree in external characters and in 

 anatomy, with the exception that whilst the northern form 

 possesses constantly 16 pairs of legs, the southern variety has only 

 15 pairs. It is not considered advisable to separate these two 

 forms as distinct species. They can only be considered varieties. 

 The first to be discovered and named was the southern variety, 

 which was termed Peripatus leuckarti Sang., var. occidentalis, by 

 Fletcher in 1895. 



Since that date, however, this western form has been raised to 



