KETNELL : ON BUIiTOA NILOTIOA. 199 



provided with a cfecum (Fig. 2 A, C^.) close to its junction with the 

 albuminiparous gland, has the common folding, the ovotestis itself 

 (Fig. 2 A, Ot.) being made up of six or more lobes of varying sizes, 

 and more or less free from one another, and distinct. This gland is 

 easily visible on account of its dark purple-black colour. Both the 

 gland and its duct are enveloped in connective tissue, quite free from 

 the liver, and in consequence there is no difficulty in their isolation. 



But little could be made of the embryos contained in the shells, 

 many of the largest of which 1 examined in the hope of finding some 

 in a fairly advanced state, but in each case the podocyst enveloped 

 practically the whole. In the more advanced specimens the first coils, 

 amounting to from a turn to a turn and a half, were distinct, owing to 

 their being covered with a very thin, pale-green chitinous shell, 

 situated at the apex. In some other cases the first coils were devoid 

 of visible covering, though well formed and situated some distance 

 below the apex, and protruding through the enveloping podocyst. 

 Just under the shell, and exterior to it, are two papillae which may be 

 the rudiments of tentacles. Under these, again, is a distinct transverse 

 slit, a possible oral opening.. The action of the spirit had caused the 

 embryos to become quite opaque and very brittle, thus adding to the 

 difficulty of examination. 



Jaw (Fig. 3 A) more compressed laterally and not so arcuate as in 

 Achatina, with three or four coarse ribs in the centre, more or less 

 finely striated vertically over the rest of the surface. 



Kadula (Fig. 3 B) having about 62-1-62 teeth in a row in the 

 widest part. Centrals narrow (Fig. 3 C), without cusps; laterals 

 1-34 (Figs. 3C andD) on each side, tricuspid, at first distinctly, the 

 entocone gradually becoming reduced till the 34th tooth is 

 reached, after which it ceases to exist as a cusp in most rows, but in 

 some it disappears somewhat earlier. The last 2h teeth in the row 

 degenerate very rapidly, both the mesocone and ectocone becoming 

 smaller and smaller till the margins are reached. The mesocones 

 overlap the bases of the teeth in front of them, but this does not apply 

 to about the 25 outermost teeth on each side. 



Remarks. — Without taking into account the shell character's, the 

 anatomy of Burtoa Nilotica shows its undoubted alliance with the 

 Achatininse, as might be expected from its geographical range. It 

 agrees with Archachatina, Cochlitoma, Achatina, Liniicolaria, and 

 Atopocochlis in the median teeth of the radula being narrow, and with 

 Cochlitoina, Achutina, and Atopocochlis in tlie laterals being more or less 

 tricuspid, though in Cochliloma Crawfordi, examined by H. A. Pilsbry, 

 the inner pair of laterals had entocones without well- developed cutting- 

 points. 



The jaw seems to vary too much in all the genera that have been 

 examined to form much basis for classification at the present time. 



The most important peculiarity is, without duubt, the point of 

 insertion of the penis retractor. Limicolaria is nearest in agreement 

 in this, but I have not been able to find the actual place of 

 insertion in the lung-floor mentioned in any of the works consulted. 

 In Cochlitoma Crawfordi Pilsbry found the penis retractor attached 



