MR. B. GARNER ON THE SHELL-BEARING MOLLUSCA. 41 



the structure of the Turbonidae very prettily aud in small compass 

 particularly iu the very long spiral tongue. Delpliinula has the 

 fringed mantle and sides aud very vronderfuUy armed tongue of the 

 other Trochidse. Melania is of similar organization to our well- 

 known Paludina, the stomach compound, the mantle and bilobed 

 head fringed, and the latter marbled like that of Paludina. Ampul- 

 lar ia appears to be truly amphibious. 



8. BucciNUM, ^c. — Natica presents much the same structure 

 as the common Buccinum, but has a muscular disk anterior to the 

 mouth, — a disposition, with some variations however, found in other 

 mollusks. The first and second stomachs are at a distance from 

 each other, the tongue is little developed, and the branchiae (often 

 single in the Turbonidae) two in number. Purpura also differs 

 but little from Buccinum. Ovula is a less attainable mollusk : the 

 foot is long and rather narrow, and subventral rather than sub- 

 trachelian, with a sinuosity on the right of the neck, where also is 

 a short hooked penis in the male, receiving a vas deferens from 

 near the rectum behind ; there is a large and small branchia, and 

 the reflected portion of the mantle is covered witli tubercles and 

 tentacles, — no doubt a fine garnish in the living animal ; the mouth 

 has a muzzle, and there are small eyes on the external sides of the 

 curved, awl-shaped tentacles ; the elements of the tongue are 

 beautifully toothed and serrated. 



9. Lymn^us, Sfc. — Of the air-breathing aquatic and (10) ter- 

 restrial gasteropods the most interesting particulars are their 

 generative organs, wliich the author proposes to re-examine. The 

 brain of Helix aspersa is composed internally of pyriform or 

 oval ganglionic vesicles, each giving origin to one or more nervous 

 fibres. The acoustic sacs are similar to those of Botns. The nerves 

 from the upper part of the ring are enveloped in a darkish neuri- 

 lema, and comprehend no doubt olfactory, optic, and tactile twigs ; 

 there being the buccal ganglia for taste, and the acoustic sacs for 

 hearing ; the twigs, however, forming the buccal or pharyngeal 

 ganglia have a broad double root on each side, near the origin of 

 the above three nerves. The lower part of the brain is very 

 analogous to that of Sepia, giving off nerves to the foot, and 

 external and internal respiratory ones to the mantle, respiratory 

 opening, branchiae, &c. Lymnceus has the cephalic ring formed by 

 about twelve ganglia, exclusive of two large and t^o minute ones 

 . on the buccal mass. The upper portion of the ring has gangli- 

 onic swellings, but in other respects the nerves are as iu Helix. 

 Its lower portion consists of two pedal nerves, and has the 



