258 MR. G. C. ROBSON ON THE 



at a point about two-thirds of the way from its apex downwards. 

 In z 2 the point of insertion is lower down. The penis sheath is 

 complete, and the retractor is a branch of the right ocular band. 



In the internal structure of the penis there is a marked 

 difference between the two forms. In z x the penis fits closely 

 into its sheath. In z„ the neck of the sheath through which the 

 retractor passes is very much thickened and the retractor passed 

 down it some way before it meets the penis, which is thus shorter 

 than in z t . 



2. Cochlitoma zebra var. fulgurata (Pfeiffer). 



Two specimens were dissected, measuring 115 mm. and 94 mm. 

 These are designated f 2 and f 2 respectively. 



External Features. 



(1) Shell. — The aperture is in both cases more effuse ventrally 

 than in the typical form, and the columella is sinuous in both 

 cases. The sculpture starts in f 1 on whorl 1^-lf, in f 2 on whorl 

 l|-2. The character of the sculpture was mainly based upon f 2 

 as f x was very much worn. It consists of flatfish blister-like 

 decussations of a more delicate texture and quality than in zebra. 

 As in var. obesa they are crowded at the upper sutures. There 

 is a band formed of enlarged granules running spirally round the 

 upper whorls. In f„ this is lower down on each whorl than in f . 

 There are eight whorls in each case, and the granules extend 

 as 3-5 sutural rows on to the last but one whorl in f . In f 2 

 these are only very slightly represented, though the shell is less 

 worn. The character of the colour banding varies a good deal 

 between the two specimens, but it is substantially different from 

 var. obesa. 



(2) Coloration.— A. detailed account of this feature will be 

 found in Mrs. Longstaff's paper. 



(3) Mantle-folds, etc. — The cervical lobe is broad and flat in i v 

 narrow and pointed in f 2 . The posterior lobes are not different 

 from those of var. obesa. 



The anus and pneumostome lie very much as they do in var. 

 obesa and their general character is the same. A special lobe is 

 found parallel to and below the cervical lobe which more or less 

 screens the urinary aperture as in var. obesa. 



Internal Anatomy. 

 (1) Alimentary Canal. 



The jaivs agree in both cases. They are flatly lunate when 

 viewed anteriorly. The upper surface is of the same average 

 width all the way round and is rather narrow in proportion to its 

 width. There are faint and irregular signs of broad ribbing and 

 traces of faint striation. 



The jaw is at once distinguished from that of var. obesa by its 

 narrowness and the parallel edges of its upper plate. 



