Hvrrox.— On some Branchiate Gastropoda. 197 
dentieulated on the outer side only, those of the outer marginals strongly 
denticulated on both sides. 
The specimen figured was collected at Auckland, on Zostera. The, 
eared central tooth differs from all the other species of Diloma. 
Harrorrs mis, Martyn. Pl. XV., fig. m 
Animal sooty-black ; foot deeply notched in front. Dentition, ao -5-1-5- @ 
Central tooth about as broad as long, rounded posteriorly, and eared, re- 
flexed portion without cutting-points, a long process projecting backward 
and upward on each side below the reflexed portion. First lateral broader 
than long, subquadrate, without cutting-points. Second lateral oval, 
longer than broad, without cutting-points. Third lateral long and narrow 
with a clavate process extending from the exterior side, and the whole of 
the interior side occupied by a large cutting-point. Fourth lateral like the 
third but shorter and broader. Fifth lateral oblong, transverse, with a 
blunt cutting-point on the inner side. Marginals slender, denticulate on 
both edges. 
The specimen figured was collected at Lyttelton. 
Parmornorus uneuis, Linné. Pl. XV., fig. 1. 
Dentition.—Central tooth subquadrate, broader than long, the reflexed 
portion without cutting-points.. First to fourth laterals similar, oval, the 
length three times the breadth, without any cutting-points. Fourth and 
fifth laterals large with two strong cutting-points. 
The specimen figured was collected at Lyttelton. 
Acmma coNorpEA, Quoy and Gaimard. Pl. XV., fig. x. 
Animal.—Margin of the mantle not fringed. Dentition.—Length of the 
teeth more than three times the breadth, the recurved portions moderate; 
basal plates subrectangular, much longer than broad. No accessory teeth. 
The specimen figured was collected at Sumner. 
Acoma corticata, Hutton. Pl. XV., fig. L. 
Animal.—Margin of the mantle not fringed. Dentition.—Teeth rather 
broad, the recurved portions very broad and blunt; basal plates imbricating, 
the anterior margin straight, the posterior and exterior margins deeply 
sinuated, the interior margin concave; a pair of accessory hooked teeth on 
each side. 
The specimen figured was collected at Dunedin. 
Acmma PILEOPSIS, Quoy and Gaimard. Pl. XV., fig. m. 
Dentition.—Length of teeth more than half the breadth, the recurved 
portions rather long and pointed; basal plates rhomboidal, with a central 
longitudinal groove. No accessory teeth. 
The specimen figured was collected at the Auckland Islands by Mr. E. 
Jennings, and sent me by Prof. T. J. Parker. 
