204 SPARTZBRANCHIA. 
to the branchial cavity. The body conic; the shell conic ; 
the mouth rostriform, furnished with two mandibles ; two ten- 
tacles dilated at their base externally bearing the eyes. The 
sexes are distinct, ovo-viviparous. 
All the animals of this Order inhabit fresh waters, in ponds, 
rivers, or marshes. Of their economy nothing is known. 
Synopsis Generum. 
Testa spira depressa, infra apertissime umbi- 
CAMA oe et btw ae see pe es ee 
Testa elevata. Sutura profunda. Apertura 
rotunda 21... os cme po Seve es oe | ee 
Testa conicé elevata. Spira acuta. Sutura 
protunda........ 96. Biruynta. 
All the pals of fig Or au are OVO-V Sass and. have two 
tentacles more or less contractile ; the right tentacle is thicker 
than the other, and is pierced at its extremity for the exit of 
the verga. Between the tentacles is situated a fleshy short cy- 
lindric rostrum. 
The aperture leading to the branchial cavity is situated on 
the anterior margin of the mantle ; the branchiz, rectum, the 
canal from the mucous gland and the matrix of the female are 
situated on the right side. The matrix terminates below in a 
fleshy hollow tubercle. 
The tongue is small and spinous; the salivary glands are 
very large ; the cesophagus rather long and straight ; the sto- 
mach is very large, and is divided into many different cavities ; 
the intestine passes upwards near to the fleshy mass of the 
mouth, it turns backwards behind the heart, and makes one 
turn before it forms the rectum. 
The branchie are composed of three ranges of conic filaments 
arranged very regularly. 
The brain is formed of two lobes connected by one slender 
nervous fibre ; the branchial nerve passes under the cesophagus 
and joins the right lobe; the other nerves are nearly similar to 
those of the families Purpuride and Turbinide. 
The verga is cylindric, very thick, surrounded with annular 
