122 
MOLLUSCOUS ANIMALS. 
Harpa rosea crenata, t. 34. /. 5. 
Harpa crenata. Swainson. App. Bligh. Cat. 5. 
Inhab. Pacific Ocean. 
Lesson in the Illustrations of Conchology has given it another name. 
Harpa minor b. gracilis, t. 36. /. 17. 
Harpa gracilis. Brod. & Sow. Zool. Journ. iv. 373. 
This shell, of which I have seen three or four specimens, is certainly only a small slender variety of 
H. minor. The specimen figured is in my private collection ; it is rather larger than Mr. Bland’s, noticed by 
Mr. Broderip. Length, 1 inch, 2 lines; diameter half an inch. In colour and form it exactly agrees with the 
type species. 
PURPURA. 
The mantles end in a short groove in front, which slightly extends beyond the shell when the animal 
walks, and is furnished with a short groove behind. The foot short, longest in front. The tentacles are long, 
linear, dilated and united together at their base, as if they sprang from the same place, as long as the front of 
the foot, with the eyes placed a little above the middle of their outer side. The operculum is horny, and 
bends so as to fit the pillar ; and when the animal is walking it is placed against the worn part of the pillar lip. 
Montagu observes that the ends of the tentacles as far as the eyes are retractile, in the same manner as 
those of the snail. I have often examined the animal alive, but have not observed this fact. 
The egg of the common P. Lapillus has been described under the name of Hydra triticea. 
Our species is found on rocks, often quite as high as high-water mark, so that they are out of the water 
the greater part of their lives. 
Adanson in describing the animal of this genus observes that the two sexes can be distinguished by the 
ventricoseness of the shell, an idea that has been adopted by De Blainville; 
Purpura crassa. Blainv. Mon. t. 12./. 4. 
Purp. raelares. Duclos. Ann. Sci. Nat. t. 1. /. 2. 
Inhab. Peru. 
Purpura clathrata. Blainv. Mon. t. 12./. 6. 
Purp. canaliculata. Duclos. Ann. Sci. Nat. t. 1./. 1. 
Purpura trochlea. 
This shell has generally four spiral ribs on the last whorls, the front one being the smallest. I have spe- 
cimens with the front and next and last, one with all the ribs wanting, when the shell is regularly spirally 
striated. 
Purpura sacellum. (Lam. 241?) 
Murex sacellum. Chemn. x./. 1561-62. — W. C. t. 25. /. 20. 
Purpura Thiarella. Lam. 246. (fide tab.) 
Inhab. Pacific Ocean. 
