112 Transactions of the Royal Society of South Africa. 



Nearest to G. denticulatiis (Dhrn.) {=ordinanus Smith) and G. gibbonsi 

 Taylor, but difiering from both by reason of its rather less distorted axis. 



Subgenus eustreptaxis Pfr., 1878. 



Gonaxis {Eustreptaxis) elongatus (Fulton), 1899. 



(Plate V, figs. 1-3.) 



1899. Streptaxis elongatus Fulton, Proc. Mai. Soc. iii, p. 302, fig. 2. D.F. 



Hab. L. Marques. District north of Macequece (Cressy). 



This fine species was founded on a couple of shells from an unknown 

 locality ; it is therefore satisfactory that its true habitat is determined. 



The parietal tooth appears to be formed after maturity, as I have seen 

 a specimen in which the reflexion of the peristome is practically complete, 

 but with no sign of the dental process. Young shells are clearly perforate 

 to the apex. 



The average size of the species is about 23 X 14 mm., but I have seen an 

 individual as large as 28 X 14| mm., rather suggesting the result of a cross 

 between elongatus and vengoensis. 



Some notes on the anatomy of a young specimen are given below : — 



External features and pallial organs. — The foot-sole is undivided, and 

 there are no peripodial grooves. The hind end of the foot is bluntly 

 pointed. There is no keel, but a median posterior groove is present. The 

 two anterior dorsal grooves are rather close together, and, on each side of 

 these, other grooves run forwards and slightly downwards on the neck 

 (PL V, fig. 1). The two lower tentacles are apparently bifid, as is sometimes 

 the case in carnivorous snails. 



The right body-lobe is rather large ; the left is divided into a broad 

 right portion, and a small, triangular left portion, as shown in the upper 

 part of fig. 1. 



The main pulmonary vein has a number of slender branches. The 

 kidney seems to be rather short. The ureter arises from the front end of 

 the kidney, runs back along its upper edge, and then curves round and 

 runs forward just below the rectum. It appears to be closed throughout. 



Internal characters. — The pedal gland, which lies in the lower part of 

 the body-cavity, is long and somewhat contorted. It is broad for the 

 3 or 4 mm. of its length that lie in front of the ventral nerve-ganglia ; but 

 the remaining portion, about 6 mm. long, is much narrower, although still 

 having some glandular tissue. 



The cerebral ganglia are much longer than broad (their length being 

 measured in an antero-posterior direction). They are close together, and 

 in the specimen examined they lay in front of the opening of the oesophagus. 



