MOLLUSCA OF INDIA. ^1 



and on the side. It gave one the impression that the power of 

 sight in these creatures is very limited, and is perhaps less than 

 that of the air-breathers having the ej'e at the extremity of the 

 tentacle. Foot is somewhat pointed, mouth large." 



Having received from Mr. W. T. Blanford a spirit-specimen of 

 Cyclophorus wahlhenji, Benson, from Natal, which had been given 

 him by Mr. J. Pousonby, I have been led to make a comparison of 

 the animals of some other species of Ct/clophorus and Cijdostomd in 

 my collection. A very cursory examination of this Africnii species 

 served to show a very remarkable divergence of structure in the 

 position of the male orjian, as compared with those species I was 

 familiar with, from the North-east frontier of India, such as Ci/rlo- 

 jphorus aurora, Bs., the male and female of which I figured on 

 Plate LI. Part V., and merely referred to on p. 165; also a 

 divergence in this respect from a description of Spiraculam his- 

 pidum and drawings I made at the time from life. In both these 

 species (C aurora and S. Mspidum) the male organ is on the 

 right side of the head, below the right tentacle (iri(/e Plate LI. fig. 1). 

 I fortunatelj- had spirit-specimens of C. (Cydoheli.v) crocatus, from 

 the Nicobar Islands, sent me by my brother, Mr. Harold Godwin- 

 Austen ; this, although having a shell so very unlike any species 

 known on the Indian mainland, proved to be quite similar as re- 

 garded this part of the reproductive organs in the male ; and I ;im 

 therefore led to think, from analogy, that C. foUaceus from the 

 Nicobars will be found to be structurally the same, although the 

 shell shows even a greater departure from typical Cijdophorus. In 

 C. ivahlheryi the male organ is in a very different position, much 

 nearer to the anus and on the centre line of the neck, quite far back 

 under the edge of the mantle. The second considerable point of 

 difference is found in the form of the operculum, when compared 

 with crocatus ; it is quite smooth internally, and very evenly, re- 

 gularly, and broadly concentric, the scar left; on its removal being 

 a smooth plane surface. Now in crocatus the operculum is very 

 flat, and has a strongly developed boss on the inside, which fits into 

 a well-marked pit in the scar, and it is very indistinctly concentric 

 in front. In C. pearsoni, Bs. (Conch. Ind. pi. xlviii. lig. 5), and 

 Jchasiensis, Nevill, Hand-list, p. 273. no. 4H,=siamensis (Conch. 

 Ind. pi. xlviii. [not good] fig. 7) (being a misnomer, for it is not 

 found in Siam), a similar but much smaller papillate central nucleus 

 is seen, in front narrowly and closely concentric. In C. aurora, 

 however, the internal side is very slightly convex, and the central 

 nucleus is reduced to a minute size ; in G. bonieensis I find a small 

 central boss. In the shell of C. wahlbergi we are presented with 

 a third point of divergence, in the acutely edged peristome of the 

 African moUusk. 



So great a difference in the structure of the animal, involving a 

 considerable modification of adjacent parts, combined with the two 

 other marked characters of shell and operculum, are, I consider, of 

 sufficient importance to constitute wahlbergi the type of a new 



