122 Mr. W. Clark on the Muricidse. 



Murex Ginannianus, nobis. 



Pleurotoma Ginannianum, Philippi. 

 Fusus XJlidianns*, nonnuU. 



Animal spii-al, ground colour white or pale yellow; mantle 

 plain, even, except the branchial fold, which, when the animal is 

 in motion, floats free beyond the canal, and from its constant 

 movement appears to act as a feeler ; the mantle also at the up- 

 per part of the outer lip lines a very inconspicuous emargination 

 of the shell, forming a minute anal conduit. The head is small, 

 white, compressed, and does not at all interfere with the basal 

 conjunction of the tentacula ; the proboscidal fissure, as in Murex 

 undatus, is below the coalescing membrane ; the tentacula are 

 short, flake-white, with eyes at the terminal surface of external 

 offsets nearly extending to their points. The foot when fully 

 extended reaches to the third or fourth posterior volution ; it is 

 pale yellow below, with marginal transverse white markings, and 

 on the upper surface sprinkled with intense flake-white spots ; it 

 is subrotund in front, scarcely auricled, narrow, gradually taper- 

 ing to a blunt slightly emarginate point. There is no opei-culum, 

 and in this respect and in all the other organs it agrees with 

 Murex gracilis. 



I might have generalized in this species, but I am obliged to 

 give a somewhat more detailed account of it than usual, as it is 

 to be the standard of comparison with the two next species, with 

 which it has been considered identical by some conchologists. 



I have personally dredged this species in the laminarian zone 

 off Budleigh Salterton. A larger variety is taken occasionally in 

 the deeper waters of the coralline zone, which I am inclined to 

 think may turn out a distinct species. The organe geuerateur 

 is precisely similar to that of Murex gracilis. 



Murex nebula, Montagu et nobis. 



This animal has the closest alliance with M. Ginannianus, 

 therefore only the very doubtful and almost inappreciable varia- 

 tions will be mentioned. In this species the eyes appear larger 

 and the tentacula proportionately shorter than in M. Ginannianus. 

 The general aspect of the shells of the two species appears to afford 

 even better specific distinctions than the animals. In August 

 1849 I dredged in Littleham Cove near Exmouth, in the lami- 

 narian zone, several specimens both of the M. Ginannianus and 

 M. nebula in company, and at the same haul; they proved 

 lively and afforded a good examination for some hours ; and the 

 differences between them with respect to the shells are, that the 

 M. Ginannianus is less slender, the aperture more patulous, and 



* For Ulidianus, see ' Annals,' vol. xv. p. 316. 



