1861.] M. O. A. L. MORCh's review of the VERMETIDyE. 335 



A small group from Gaboon, corresponding to the description and 

 figure of Adanson's " Vermetus,'^ shows internally spiral lamellse, 

 proving its identity with Petaloconchus, Lea. 



I have convinced myself, by comparison of numerous specimens, 

 that the presence or absence of laminte are not even of specific value, 

 although their forms, when present, afford characters of some value. 

 The individuals seem to undergo changes with age, analogous to 

 those of the genus Cyprcea. The laminae seem to be dependent 

 on a thin, white, soft layer, sometimes covering the whole interior ; 

 they are mounted on a small elevated line in the mass of the shell ; 

 and one, sometimes compressed and sharp, is always found on the 

 median part of the columella. These lamellse must be regarded as 

 a kind of septa, or perhaps as a muscular attachment analogous to 

 the cup of the CalyptrceidcB, as first advanced by Carpenter ; but I 

 have not observed any attachment in specimens in sjnrit. The 

 animal occupies only the space near the columella, leaving the outer, 

 often much larger space empty ; the last whorls are quite filled out 

 by the animal. The laminae are most frequently present in the 

 median whorls, wanting in the first and last whorls ; sometimes they 

 are continuous to the aperture, but never when the last whorl is 

 raised in an erect tube. The size and thickness are very variable in 

 one and the same individual, sometimes very broad, nearly touching 

 each other, whilst in the foUovring and preceding whorls they are 

 very short, leaving a large gap between them. 



Septa are rarely met with. Carpenter mentions in Petaloconchus 

 cochlidium, a septum traversed by the laminae. Sowerby first re- 

 presented a Vermetus glomeratus closing the aperture with a sep- 

 tum, turning the convexity upward, and provided with a narrow cen- 

 tral opening. Dr. Gray* supposed it to be the production of some 

 parasitical animal f, induced by the fig. 18. pi. 57 of Delle Chiaje ; 

 but the discovery of Bhizochilus led him to regard it as a pecu- 

 liarity of the species. I have only once seen a similar instance, in a 

 detached specimen of Vermetus varians, D'Orb., from St. Thomas 

 (coll. A. H. Riise). The septum, constricted a little below the free 

 margin of the aperture, has a short narrow slit, not provided with 

 teeth like Dr. Gray's specimen, and is of the same colour as the 

 shell, but paler ; which makes Dr. Gray's opinion very probable. 

 This suggestion is still more strengthened by some small solitary 

 spiral Vermeti, attached on Isognomon obliquum, Gm., and Tridachna 

 squamosa, having the last whorl erect and free, with the borders 

 of the aperture inflected so as to form a reniform or heart- 

 shaped opening, but transverse and much larger than the slit in 

 the preceding. The principal difference is that the walls of the aper- 

 ture are bent inward. These small shells have a single series of im- 

 pressed linear varices, like those of Pythia and Eulima ; to the left 

 of each varix the whorls are a little inflated. I have seen the West 



» Gray, Annals of Nat. Hist. viii. 1851, p. 479, pi. ] 7 B. f. 4-6 ; Froriep, Jahres- 

 bericht, 1851-52 (translation). 



t It is indeeil very like the constriction formed by Sipunculus strombi, Mout., 

 in the shell of Dentalium. 



