76 
The animal of Neolepton sangiiineum has its mantie margins 
open in front and ventrally, but coalesced posteriorly to form one 
branchial and one anal slit both with slightly elevated and densely 
papillate margins which are tinged with red. 
The foot has a long cylindrical sole and shortly projecting hind 
and front ends. There is no byssal groove. 
At each side two demibranchs are present, but the external 
(here posterior) one is much reduced in size and consists chiefly 
of the reflected lamella. This is combined with the direct one by 
means of a few interlamellary junctions. The inner (here anterior) 
demibranch has both its lamellae well developed, and has no in¬ 
terlamellary connections. Both gilis are entirely smooth and have 
their filaments directed from behind towards front. 
Montacuta unidentata n. sp. 
(PI. II, figs, 48—51.) 
Shell small, rather solid, elongate-ovate, white, finely concen- 
trically striated. Umbones broadly rounded. Anterior end much 
longer than (about twice) the posterior one, frontal margin rounded, 
posterior one subtruncate, antero-dorsal margin straight, basal mar¬ 
gin faintly curved. Lunula obsolete, very narrow, most distinet in 
the left valve. Interior white, smooth, margins simple. Hinge-line 
narrow, that of the right valve sharply edged but strengthened 
inside by means of a ridge (=inner margin of hinge plate); no lateral 
teeth, except a single strong cardinal-like one of a broadly trian- 
gular shape, in front of the deep, rounded trigonal ligamental pit; 
left valve with a short anterior and a posterior lamella fitting inside 
the right edge, the former gradually rising to an elongate lateral 
tooth. Resilium short. Adductor scars ovate, the anterior more 
narrow and elongate than the posterior one. Pallial line simple. 
Dimensions: L. 2.8, h. 2, crass. 1.4 mm. — Locality: Stewart Is¬ 
island: 36a, numerous valves. 
S u t e r (1913) described a Montacuta triquetra from Port Pe¬ 
gasus, which differs essentially in its shape, being more triangularly 
elevated. 
