148 



Inlia'i)its the back parts of Mancliester. 



Mean divergence about 130° ; heiglit .53 inch i greatest breadth .77 inch ; least 

 breadth .62 inch. 



No. 20. Shell white, reddish on the upper whorls, with a pale greenish brown 

 epidermis : transverse strioj very fine, wrinkled ; with minute wrinkles nearly cov- 

 ering the last whorl ; umbilical keel wanting : spire moderately elevated : whorls 

 five ; last whorl flattened beneath, making the periphery subangular ; with the 

 suture well impressed : aperture suborbicular ; effuse, pointed, and much advanced 

 above ; lip thick : umbilicus half as wide as the aperture. Operculum unknown. 



Mean divergence about 130° ; height .45 inch ; greatest breadth .7 inch ; least 

 breadth .58 inch. 



Note on the genus Stoastoma. Following the sugges- 

 tion of Dr. PfeifFer, (Zeitschr. Malak. 1849, p. 113,) I recog- 

 nize the genus Stoastoma in the well-known Cyclostoma suc- 

 cinetim Soivb. It appears to me, however, that Dr. P. has 

 gone too far in saying that this species may be taken as the 

 chief type ('• Haupttypus ") of the new genus. It differs from 

 all the species of Jamaica, in having the labrum sharp and not 

 produced beyond the labium, in the manner which suggested 

 the name of the genus. Stoastoma succineum might there- 

 fore be considered as the type of a Polynesian subgenus, 

 which has about the same degree of affinity to Stoastoma 

 proper, that Partula has to Bulimus. 



Stoastoma Vilkinsoni^. Shell subdiscoidal : pale horn 

 color, subtransparent : with five spiral carinee, of which one 

 runs into the suture, and one appears on the middle of the 

 whorls of the spire ; some have, in place of the last one, two 

 smaller carinse ; with very delicate spiral raised lines, usually 

 four to six in each interspace : spire moderately and convexly 

 elevated : whorls three and one-half, angulated, with a deep 

 suture ; last whorl rather large, detached from the penult 

 whorl near the aperture : aperture campanulate ; labrum pro- 

 duced very far, above abruptly produced and auriculate, with 

 wide and deep scallops formed by the produced carinas ; labi- 

 um much detached from the penult whorl and a little reflect- 



