MAZATLAN UNIVALVES 253 
322. ETHALIA AMPLECTANS, 2. s. 
E. t. minima, planatd, diaphand, nitidissima ; anfractibus 
lil, planatis, peritremati rotundato ; callositate haud parva, 
umbilicum via« tegente, juxta labium planata, semilunatd ; labro 
acuto, supra anfractum penultimum dilatato ; imfra suturam 
haud impressam callositate, suturam fallacem extus sumulante ; 
aperturé rotundata. 
As it is barely possible that this shell may be the young of 
Teinostoma amplectans, the same specific name has been given. 
It differs however in the much smaller size of the callosity, 
which in this shell displays a broad, semi-lunate planation at 
the coltmella, which appears characteristic of the species. 
Long. °016, lat. ‘04 by *032, div. 180°. 
Hab.— Mazatlan ; 4 sp. off Spondylus; L’pool Col. 
Tablet 1173 contains the freshest specimen. 
Gunus THINOSTOMA, A. Ad. 
Proc. Zool. Soc. 1858, p. 183.—H. & A. Ad. Gen. vol. i. p.122. 
Testa spird depressd, politd, anfractibus rapide augentibus ; 
. ze . ri A 7 A A . 
regione umbilicali callosé ; apertura producta, elongata, ab axi 
remota ; interstitio calloso ; peritremati axin versus rotundato, 
ad peripheriam interdwm angulato. 
Shell Rotelloid, with a greatly produced mouth and eallus. 
Tt resembles Cyclops among the Nassids, and in the appear- 
ance of the base reminds the observer of Streptaxis and 
Anostoma among the Helicidse. Having been described (in 
English only) from a single species (T. politum, St. Elena, 
8 fm. Cuming,) some of the characters before given may here- 
after prove to be only specific. 
323. TEINOSTOMA AMPLECTANS, 7. s. 
LQ. t. parva, albd, planatd, levi; peritremati rotundata ; 
callositate spirali umbilicum tegente, labium versus subplanatd, 
supra parietem intus suturam decurrente ; apertura rotundata : 
labro supra anfractum penultimun reflecto ; suturt haud 
umpressd. 
Although the shells described above as Ethalia may possibly 
be the young of this species ; yet, as they were all of the same 
June 1856. > y 
