29 



Parmophorus granulatus. PL 25. Fig. 150. Shell, showing its mi- 

 nutely recurved vertex and faint marginal sinus. 



Genus 4. SIPHONARIA, Sowerby. 



Animal; body oval, rather depressed; head subdivided into two 

 equal lobes without tentacles or apparent eyes ; edges of the 

 mantle crenulated ; branchiae in the form of a square membrane 

 in the sinus formed on the right, between the foot and the mantle. 



Shell ; ovate, sometimes elevatehj conical, uncinate at the top, 

 sometimes depressed, radiately ribbed or striated, denticulated 

 at the margin ; interior exhibiting a siphonal impression. 



A very natural group of Limpets, in which the special characteristic of 

 the animal, a branchial sinus on the right side, between the foot and the 

 mantle, is accompanied by a corresponding siphonal impression on the 

 inner surface of the shell. The conchologist, therefore, is enabled readily 

 to distinguish them, and the species exhibit peculiarities of form and ge- 

 neral aspect which strike the eye, independently of their leading generic 

 character. The genus, of which nearly forty species have been described, 

 is very generally distributed within the tropical and subtropical zones of 

 both hemispheres. 



Species. 



Figure. 



Siphonaria sipho. PL 24. Pig. 144. Shell, showing on the left side 

 the internal siphonal impression. 



