294 Transactions. — Zoology. 



Baclula tongue-shaped, consisting of about 70 transverse 

 rows of teeth, straight in the middle, shghtly bent forwards 

 on both sides. Teeth, 10—5—1—5—10. 



Central tooth asymmetrical, rectangular, not much longer 

 than broad ; reflection tricuspid, the central cusp narrow, 

 reaching very little beyond the middle of the base ; on its left 

 side a stout transverse cutting-point, directed towards the 

 left posterior corner of the base, a very small cutting-point on 

 'the right side of the cusp. The left side-cusp sinuated, with 

 a rather long vertical cutting-point ; right side-cusp rounded, 

 with a stout aiid long vertical cutting-point. 



Laterals. — The first four on each side of the central very 

 similar to it, but quadrate, the reflection larger. The median 

 cusp reaches almost to the end of the base ; on its left side is 

 a spur-like, transverse, broad and sharp cutting-point reaching 

 beyond the base, on the right side a much smaller one. The 

 side-cusps, wdiich are sinuated, have a rather long vertical cut- 

 ting-point on each, which is more developed on the right cusp. 



In all other radulge I have seen the teeth on the right 

 side of the central are the inversion of those on the left side, 

 which is not the case here. All the four laterals, on the left 

 and right side of the central, show the very same arrange- 

 ment of the cusps and cutting-points, thus rendering the 

 median part of the radula asymmetrical, as the figure indicates 

 it. The fifth lateral somewhat longer than broad, tricuspid, 

 the cusps all with one strong vertical cutting-point. 



Marginals broader than long, tridentate, the fourteenth 

 sometimes with four denticles. First not very broad ; the 

 others get much broader and shorter towards the margin. 

 Last marginal small, with two denticles. 



The central tooth and the four laterals on each side of it 

 are so widely different from all those known to me in other 

 species that I do not know whether this radula must be con- 

 sidered as abnormal or not. Unfortunately, I have no animal 

 of the same species at my disposal just now, and therefore 

 am unable to decide the question. 



Should further investigation prove it to be normal for the 

 species, the creation of a new genus would no doubt be 

 justified. Patula Jessica, Hutt., is in its shell closely allied 

 to P. xaricosa, and an examination of its dentition, which is 

 not known yet, would be highly interesting, as it might show 

 similar peculiarities. 



Patula sterkiana, Sut., var. reeftonensis, n. var. 



This variety differs from the species described in last 

 volume of the Transactions, p. 85, by its considerably-smaller 

 size and the much more distant ribs, of which there are only 

 about 15 per mm. Besides this there is no difference. 



