192 LAND AND FKESHWATER 



The jaw was only seen in the second specimen examined ; it 

 corresponds with that of the family Endodontidge, and was ex- 

 ceedingly fragile, consisting of a number of thin oblong plates, 

 overlapping each other. This single jaw was not complete, and I 

 covald only get two drawings of separate portions, one being a side 

 view of eight or nine plates. 



The odontophore was equally interesting and showed the same 

 affinities. The plates of the central teeth are square in shape, the 

 rhachidian being the narrowest ; they increase outwards in breadth 

 until the laterals are very broad, low, and oblong, whilst on the 

 outermost the cusps are difficult to detect and very irregular. The 

 centre tooth has a large pointed mesocone, with two basal cusps ; 

 the median teeth up to the eleventh are similar in shape, but with 

 only one cusp on the outer side; the next, the twelfth, shows an 

 inner side cusp ; in the thirteenth and fourteenth the mesocone is 

 smaller, with two equal-sized side cusps rising from the upper side 

 of the plate. In the succeeding teeth there is a good deal of 

 irregularity in profile, but the side cusps are split into two, now and 

 then three, the centre still remaining the longest or nearly the 

 longest. The dental formula is 



20 . 2 . 10 . 1 . 10 . 2 . 20 



or 32 . 1 . 32 



I have received from Mr. Collett, from the Ambegamuwa District 

 of Ceylon, specimens in formalin named Microcytis thwaitesi, Pfr., 

 and M. suavis, Jousseaume. The tube containing suavis bears this 

 remark : " I have sent Mr. Sykes Dr. F. Jousseaume's type of this 

 species." Mr. Sykes, in a paper on Cejdon Land-Shells, Journ. 

 Malacol. Soc. London, vol. iii. no. 2, p. 65 (1898), refers to these 

 species ; and I cannot do better than quote the conclusion he came 



^Q. " Pfeiffer, in 1853, described* Helix tJmaitesi, and Keeve 



gave a figure of itt drawn from an example in the original type 

 series ; Dr. Jousseaume, in 1894 +, described Microcystis suavis 

 from NuAvara-Eliva. I have examined specimens said to have been 

 identified as M. thwaitesi and M. suavis by Dr. Jousseaume, and 

 also Pfeiffer's t5i)es, and come to the following conclusion : that 

 Dr. Jousseaume"s M. thwaitesi is not that species, but is my Macro- 

 chlamys circumscnlpta ; while his M. nuivara is really 31. thwaitesi, 

 as is also his M. sjiavis. This latter appears to be a variety, with 

 the spire a little more depressed, the umbilicus a trifle larger, and 

 the mouth slightly different in shape : it may be of varietal, 

 certainly not of specific rank." 



The specimen labelled M. thwaitesi sent by Mr. Collett agrees m 

 every way with M. circumsculpta, and I shall describe the animal 

 under this last title. 



The result of my examination of these molluscs has proved 



* Proc. Zool. Soc. 1853, p. 125. 

 t Conch. Icon., Helix, sp. 1336. 

 + Mem. S<jc. Zool. France, Tii. p. 10, pi. iv. fig. 3. 



