91 



THE ANATOMY OF TWO SPECIES OP HELICARION FROM 

 TROPICAL AFRICA. 



By Hugh Watson, M.A. 

 Read Uth May, 1920. 

 Through the kindness of Dr. Peringuey and Mr. K. H, Barnard, of 

 the South African Museum, Cape Town, of Sir Sidney Harmer, K.B.E., 

 and Mr. G. C. Robson, of the British Museum, and of Major M. 

 Connolly, I have lately been given the opportunity of investigating 

 the anatomy of two African species of Helicarion, an opportunity of 

 which I am very glad to avail myself, seeing that so little is known 

 about the Zonitidse of Tropical Africa. 



My description of H. gomesianus (Morelet) is based upon the 

 examination of a single specimen belonging to the South African 

 Museum, and kindly sent to me for dissection by Major Connolly, 

 who informs me that its shell bears a very close resemblance to 

 three shells of H. gomesianus from Pungo Andonga, Angola, which 

 the late King of Portugal presented to the British Museum. The 

 specimen was found at Pemba, a village or mission station in 

 Northern Rhodesia, in what was formerly known as the 

 Mashukulumbe country, about 120 miles north-east of Livingstone 

 and some 30 miles north-west of the River Zambesi, 



The second species is one of which several examples were 

 presented to the British Museum in 1910 by Mr. F. J. Jackson, C.B., 

 having been collected in British East Africa, " probably at Nairobi." 

 Major Connolly considers that this species is probably one which 

 has not yet been named. There can be no doubt that it differs 

 from all those of which any part of the anatomy has been described, 

 and it cannot be certainly identified with any of the species at 

 present only imperfectly known from descriptions and figures of 

 their shells. I am therefore regarding it as new to science. 



Helicarion gomesianus (Morelet). ^ 



Pemba, Northern Rhodesia. 



PLATE III. 



Shell depressed, paucispiral, imperforate, yellowish-green, and 

 extremely thin, the basal region being practically membranous. 

 Spire slightly raised, suture rather deep, whorls three, rapidly 

 expanding, rounded at the periphery, and crossed by fairly well- 

 marked lines of growth. Protoconch with microscopical spiral 

 sculpture.^ AjDcrture large, ova], 12 mm. in breadth ; peristome 

 thin and simple, Altitude 6 mm. ; breadth 15 mm. 



1 Vitrina yomediana, Movelet Voy. Welwitsch, Moll. terr. etfluv., 1868, }). 52, 

 pi. i, fig. 2. 



^ The shell was not in sufficiently good condition to enable me to describe 

 its microscopical sculpture in greater detail. 



VOL. XW.— SEPTEMBER, 1920. 7 



