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ON BURTOA NILOTIC A (PFEIFFER) AND ITS RELATIONSHIP TO 



ACHATINA, ETC. 



By Alexander Reynell, 



Read 8th June, 1906. 



PLATE XVII. 



In the early part of last March Mr. E. A. Smith kindly offered me 



the opportuuity, which I was pleased to be able to accept, of examining 



the anatomy of the above animal, which is, as far as he or I can learn, 



unknown. 



The specimens, three in number, came from Bumako Island, situated 

 in the northern part of the Victoria Nyanza, west of Entebbe, which 

 is on the north coast. They were preserved in alcoliol, in very good 

 condition, but unfortunately two of them, owing to the quantity of 

 eggs they contained, could not be extracted entire. The third one, 

 received later, was fortunately extracted by Mr. Smith almost entire, 

 and contained no eggs. The general anatomy bears a very strong 

 resemblance to that of Achatina, but it seems very possible that the 

 functional condition of the organs must have some effect on their 

 apparent shape and position to a greater or lesser extent. Too much 

 attention should not be paid to the sliape of such parts as the 

 spermatheca, oviduct, etc., for comparative purposes, unless one 

 has the supposed different genera and species in more or less identical 

 functional condition. 



E.xternally, the visible soft parts of Burtoa, in the contr;icted 

 condition as I had them, are similar to AcJiatma. The animal con- 

 tracts in the same manner, the foot being folded together longi- 

 tudinally. The top of the foot is distinctly flattened by the weight 

 of the shell, more so than in the specimens of Achatina which I have 

 had the opportunity of examining, viz. E'raussi. 



This flattening varies considerably in the three specimens above 

 mentioned. In one case it is particularly noticeable for a distance of 

 21 mm. from the hinder edge of the collar, the surface rugosities being 

 very much obliterated ; but whether this area is specialized to the 

 same extent as has been noticed in Archachatina, mentioned by Pilsbry 

 (Man. Conch., vol. xvii, p. xii), I am unable to state, not having had 

 the opportunity of examining any of the species belonging to this 

 group. 



The lung (Fig. 1), as in Achatina, is short, very richly veined on 

 both sides of the pulmonary vein (Fig. 1, P. V.), which has no large 

 branches. This veining varies very considerably in different animals, 

 as is apparent from the three I examined. The kidney (Fig. 1, Ne.) 

 is a long tongue-shaped organ, having its anterior end rounded, and 

 being twice the length of the pericardium. 



The ureter (Fig. 1, Vr., TJ. i) takes the usual course as in Achatina, 

 and is closed throughout practically its whole length ; but in the 

 cloaca, at the point wliere the rectum opens into it, there is a large 

 delta-shaped muscular fold on its upper side (Fig. 1 A, M.F.), which 

 must direct the discharge from the kidnej', on leaving the ureter, 

 more or less into the grooves (Fig. \ h., F.\, F. ii) formed b)- it and the 

 walls of the chambers. 



