1873.] MR. R B. WATSON ON MADEIRAN MOLLUSKS. 385 



Hab. Gorgulho, shore; Santa Cruz, 10-15 fathoms; Machico, 

 10-15 fathoms; Piedade (Cani§al), 15-35 fathoms; Ponta de S. 

 Lourenco, 25-45 fathoms ; Porto Santo, up to 50 fathoms. 



This species extremely resembles R. pulcherrima, with which I at 

 first associated it, till Mr. Gwyn Jeffreys's practised eye discerned the 

 difference in some specimens I had sent him. The two are unques- 

 tionably different. They are most easily distinguished by the former 

 being spotted, while this is banded ; but as I have two specimens of 

 this species in which the bands have broken somewhat into spots, the 

 rich chestnut stain at the centre of the base and on the belly-lip must 

 be noted. Its difference from the little-known species R. cossurce, 

 Calcara, specimens of which I owe to the kindness of the Marquis de 

 Monterosato, requires particular notice. Put together, they cannot 

 be confounded ; of nearly the same size, they differ very much in 

 form. R. cossurcB is comparatively small in the base and last whorl, 

 minute in mouth, stumpy in spire and apex, second and third 

 whorls broad, all the whorls closely rolled together ; its colour is 

 crimson, not chestnut. The central spot on base and belly-lip is 

 much larger in R. cossurce ; the spiral scratches on the whorls are 

 more distinct ; there are no sharp frettings below the suture. On 

 the embryonic whorls I failed to distinguish any microscopic lines, 

 which in R. perminima are easily seen. R. cossurce (if the mouth 

 be excepted) suggests a miuute R. cingillus, while R. perminima 

 approaches R. pulcherrima. 



Compared with R.fulgida, which in colour it somewhat resembles, 

 this is much longer and narrower. The whorls are not nearly so 

 rounded ; suture not at all deep ; spire attenuated ; apex more 

 pointed ; mouth not round, but oval and pointed above ; and there 

 is an umbilical chink. Mr. Gwyn Jeffreys regards this species as 

 the R. perminima of Manzoni. 



<r iyLc dj.9, Rissoa abjecta, Watson. (Plate XXXVI. fig. 23.) 



Shell conic-oblong, small, white, opaque, rather strong, with com- 

 plete peristome. 



Sculpture. Longitudinal lines of growth a little bent, microscopic, 

 with here and there a line somewhat stronger than the rest. Spiral 

 frettings minutely microscopic, very faint and superficial. The first 

 two whorls, which are embryonic, seem to have a few spiral lines or 

 scratches. 



Colour opaque yellowish or creamyish white, quite uniform except 

 that the embryonic whorls are rather yellower. 



Whorls 5-6, flattened, but slightly rounded, with a very faint 

 tendency to angularity below. The two embryonic whorls are very 

 markedly smaller than the third, out of the middle of which they rise 

 as a little cone, which seems to be truncated in consequence of the 

 excessive minuteness of the extreme tip. 



Suture rather straight, thread-like, slightly channelled. 



Mouth oval, smallish, scarcely contracted on the belly, slightly 

 pointed above. 



Outer lip gently rounded, not patulous, sharp but not thin. 

 Proc. Zool. Soc— 1873, No. XXV. 25 



