124 Dr. M. Laurie on the 



membrane, the outer layer of which is easily recognized by 

 the enormous flattened nuclei of the cells as the " serous 

 membrane," the inner membrane being the amnion. In 

 Euscorpius we find these two membranes closely surrounding 

 the embryo, and in early stages extending beyond the 

 embryonic area over the yolk. In Scorpiops, however, there 

 is no yolk, and the membranes surround a space at one end 

 of which the embryo is developing. My specimen was in a 

 comparatively young stage, and the embryo only occupied 

 about one fourth of the space surrounded by the embryonic 

 membranes. The walls of the ovarian tube are very thick and 

 the cells probably secrete nourishment. 



As there were embryos present there were only eggs in a 

 very early stage of formation. Judging from them, the eggs 

 seem to be formed in a pedunculated follicle, and not sessile 

 on the ovarian tube, as in Euscorpius. 



This type of development brings this form into close rela- 

 tionship with Vejovis, in which, as I pointed out in my former 

 paper, there is little or no yolk. The absence of yolk and 

 the pedunculated ovarian follicles give us a transition form 

 towards the katoikogenic type of development. 



lurus Dufoureius (Brulld). (PI. IX. fig. 1.) 



Of this form I have unfortunately not been able to get any 

 embryos. The ovarian tube (fig. 1) is very large and contains 

 a considerable amount of coagulura. The unfertilized ova of 

 my specimen are very small, measuring '15 millim. by 

 •1 millim. They are contained in a follicle borne on a stalk, 

 and in this, as in their small size, resemble the structure 

 found in Scorpiops. I believe the ova were ripe and had 

 attained their full size, because the surrounding follicle-cells 

 were apparently degenerating. I have no doubt the develop- 

 ment will prove to be very similar to that of Scorjn'ops. 



B. Katoikogenic Forms. 



Hemiscorpius lepturus^ Pet. (PL IX. fig. 2), and Diplo- 

 centrus Whitei (Gerv.). 



Of these two genera, representing subfamilies in Pocock's 

 classification, I have only been able to get ovaries containing 

 unfertilized eggs. 



The structure of the diverticulum, appendix, &c. in both 

 these species so closely resembles that of Scorpio and other 

 forms that I have no doubt the development is katoikogenic, 

 but no further details could be ascertained. 



