A NEW SPECIES OF PENTASTOMUM, 187 



The Female Organs. 

 But little is to be said on this subject, because these organs were in a very 

 unsatisfactory state of preservation. They consist of — 



1. The Ovary. 



2. The Oviducts. 



3. The Keceptacula Seminis. 



4. The Vagina. 



1. The Ovary (PI. XXVIII. fig. 18) occupies a position exactly corresponding 

 to that of the testis, but is very much smaller. It is in fact at this stage of the 

 animal's growth merely a narrow tube, about 0*015 mm. in diameter, passing 

 with a sinuous course down the median dorsal line. It is attached by a 

 mesentery similar in structure to, but much thicker than, those which support 

 the testis and intestine (PL XXVIII. figs. 3, 14, &c). 



It consists of a thin layer of small nucleated cells, and has a considerable 

 lumen ; but I was unable to make out anything regarding the development of 

 the ova. 



2. The Oviducts are two in number, and like the vasa deferentia, pass round 

 the intestine, and eventually meet in the middle line below it (PL XXVIII. 

 fig. 16, o.d), where they open into the vagina. 



In structure they seem to resemble the ovary itself. 



3. The Receptacula Seminis (PL XXVIII. fig. 16, r.s) are two flattened 

 oval sacs, nearly 1 mm. in length, and situated one on either side of the middle 

 line immediately posterior to the oviducts. Anteriorly, and towards the 

 median line, the cavity of the sac enlarges, and into this dilated portion projects 

 a papilla on which opens, by a stellate orifice, the tube by which the sac com- 

 municates with the vagina. 



The cuticular lining of the vagina could be followed to this orifice, but I 

 could find no trace of it on the interior of the sac ; the wall of which consists 

 of a very compact mass of minute nucleated cells ; it is about 025 mm. thick 

 on the average, and is lined with what appear to be the remains of an epithelial 

 layer. 



4. The Vagina (PL XXVIII. fig. 16, v) is simply a narrow tube, which 

 passes directly backwards from the point of union of the oviducts to open in 

 the ventral line within a millimetre of the anus. Typically it lies in the ventral 

 median line, but in one specimen of which I made sections, it lay at one side, 

 between the hook-gland and the muscles of the body- wall. 



It has a lumen of about 0*008 mm., and is lined by a delicate layer of 

 cuticle, immediately external to which is found as usual a layer of columnar 

 epithelial cells. These again are surrounded by another layer, made up of 



