Mr. W. Clark on the Muricidae. 123 



the colour of a uniform yellow, whilst that of M. nebula is much 

 darker, and shows a still darker spiral band in the sutures. The 

 animals also differ : the M. Ginannianus has the ground colour of 

 a very pale yellow brown, suffused with a tinge of light red, and 

 the flakes with which the whole body is aspersed have a light 

 sulphur tinge ; whereas in M. nebula the ground colour is pale 

 yellowish white shot with slight hues of red, and the flakes are 

 snow-white : these differences are certainly not very important, 

 but they do not appear to depend on differences of food and 

 habitat, and they are constant in the two species ; I am therefore 

 rather inclined to think that there may be sufficient grounds for 

 specific distinction. There is no trace of operculum, and in other 

 respects they closely agree with the type, except that here the 

 pleurotomic sinus is very inconsiderable. 



Murex brachystoma, nobis. 

 Pleurotoma hrachystomum, Philippi. 



The P. brachystomum of Philippi, recorded in the 2nd vol. 

 p. 169 of the ' Enumeratio Moll. Sicilise,' appears to be distinct 

 from M. Ginannianus, judging from the characters of the shells, 

 which exhibit greater distinctive marks than the animals ; we 

 have examined the two alive, and the only perceptible difference 

 is in the colour, which in this species is pm-e hyaline, without 

 the least effusion of the pale red or yellow brown which is appa- 

 rent in M. Ginannianus, and the snow-white flakes on the upper 

 part of the foot are veiy distinct, and do not run into each other 

 as in its congener. In all other respects the two are identical as 

 regards the markings and coloration of the organs that have 

 not been mentioned, and in the shape of the foot and tentacula, 

 and position of the eyes. 



At Exmouth the two are taken together in the coralline zone. 

 The M. Ginannianus also occurs commonly in the laminarian 

 zone in company with M. nebula, but in that habitat we never 

 met with the M. brachystoma. It must be admitted that the 

 specific distinctions between these species are even less import- 

 ant than those between M. Ginannianus and M. nebula ; the 

 shells exhibit some distinctive characters, the animals nearly 

 identical ones, consequently we are bound to consider the ani- 

 mal diagnoses of preponderating value, and pronounce the two 

 to be varieties of the same species. 



Murex linearis, Montagu et nobis. 

 Pleurotoma aut Fusus, auctorum. 

 Animal spiral ; the colour throughout is of a uniform brilliant 

 frosted white, occasionally suffused with snow-white opake mat- 



