200 CLASS III. GASTEROPODA. ORDER VII. PECTINIBRANCHIATA. 
The Murex stramineus of Linnzus, which Lamarck selected for the for- 
mation of this genus on account of its exhibiting a very distinct associa- 
tion of characters, may be regarded as being intermediate between the 
Tritones and the Rostellarig. We cannot, however, but consider that the 
Struthiolariz are more nearly allied to the latter, although De Blainville, 
refusing to acknowledge the generic distinction which that author allotted 
to it, refers them to a place amongst the former. The founder of the 
genus describes them as having a shell very like that of the Buccina; they 
differ however, he says, in having a varix on the outer lip; he then goes 
on to remark, that the shell of Struthiolaria is the only instance of one 
having only a single varix, and refers the genus for this reason to his fa- 
mily of the Canalifera. Now this marginal varix (if it can be called a 
varix at all,) is not in any way analogous to the varices of the Tritones or 
Murices ; it is, in fact, merely a reflection of the outer lip similar to that 
in the shell of many other mollusks, not formed until the shell arrives at 
maturity, but unusually thickened in this instance by an abundant effusion 
of enamel. Deshayes was the first to remove the Struthiolariz to the 
family of the Alata, though we believe the alteration was originally sug- 
zested by Sowerby ; and we fully estimate the affinity which the first of 
these authors traces, first with the Rostellarie, in their having the colu- 
mella rounded and ending in a beaked point ; and then with the Ptero- 
cere, in the basal canal being almost obsolete. 
The shell of Struthiolaria may be described as being of an oblong-oval 
form, with the spire regularly acuminated, and rather obtuse at the apex ; 
the aperture is obliquely ovate ; the columella, which is thickened and 
polished, ends in a very short, blunted canal; and the lip is thickened, 
sinuous, and furnished with a somewhat indistinct sinus near the canal. 
Examples. 
Pl. CCXLV. Fig. 1 and 2. 
SrRUTHIOLARIA STRAMINEA, Sowerby, Genera of Shells, No.1. Chem- 
nitz, Conch., vol. x. pl. 160. f. 1520 and 1521. Encyclopédie Mé- 
thodique, pl. 431. f. 1. a, b. 
Murex stramineus, Gmelin. 
