GODWIN-AUSTEN : ANATOMY OF HEMIPLECTA FLOWERI, ETC. 35 



detail be identical with that of the Siam species known, and under- 

 | stood by conchologists as Uemiplecta distincta. This should be cleared 

 L up, and the exact area of distribution settled. 



I must also mention I have in my collection the animal of another 



[ allied form, given me by Dr. Hungerford as H. distincta : he retained 



- the shell. It came from the Botanical Gardens at Saigon, Cochin 



China. I have dissected this specimen. There is no sign of a left 



' shell-lobe as in IT. neptuna, described above. In the generative organs 



* the male organ has a small, short, blunt coecuru and a short kalk-sac. 



. The radula differs considerably both from that described by Semper, 



; and from that of the Siam species. Thus, the central tooth and 



admedians are straight-sided, as also are nineteen of the laterals ; 



at the 35th tooth a minute notch is seen on the outside edge just 



below the point, and this becomes more developed at about the 



50th tooth. The notch gradually rises, so that at the 100th the teeth 



are evenly bicuspid and continue thus to the minute marginal uncini. 



The formula is : 



190 : 15 : 1 : 15 : 190 



The jaw has a small, but distinct, central projection. 



I The anatomy of the Siam. species now described is nearer to 



1 Uemiplecta than to Xesta, and I place it in the former, and for 



comparison I would call attention to that of Xesta citrina, from 



Amboina, and X. glutinosa (Proc. Zool. Soc, 1891, pi. v, figs. 6-6&), 



from Borneo, the shells of which are also very distinct from those 



with which I am dealing. It is not identical in all respects with 



the type of the genus (IT. Humphrey si ana), but there are many more 



of the larger shells from India, Burinah, and Siam to be examined, 



and perhaps other species will ultimately be found intermediate 



. between them. Xesta and Uemiplecta are very closely allied in 



; their anatomy. Among the large forms, Rhysota is very distinct, 



as represented by R. ovum, of which I reproduce Semper' s figure 



(PL IV, Fig. 1) to show the important differences. 



EXPLANATION OF PLATE IV. 

 Uemiplecta Floweri, E. A. Smith. 



Fig. 1. Mucous gland, x 2-25. 

 ,, 2. Portion of mantle zone near respiratory aperture, showing right shell-lohe. 

 x 2-25. 



3. Portion of mantle zone, showing left shell-lobe and dorsal lobes, x 2 - 25. 



4. ,, ,, ,, showing columellar margin lobe, x 2*25. 



5. ,, ,, ,, showing the position of the right shell-lobe on 

 the parietal margin, x 2 '25. 



6. Genitalia. Natural size. 

 6a. Male organ, x 2-25. 



7. General view, showing position of shell-muscle and mantle zone, etc. 



8. ,, ,, portion of same, x 1*25. 



9. ,, ,, showing position of some of the retractor muscles, x 1-25. 



10. Jaw. x 45. 



11. Kadula : a, median teeth ; b, inner laterals ; c, middle laterals ; d, outer- 

 most laterals, x 98. 



