Montacuta tellinula n. sp. 
(PI. II, figs. 52, 53; text-figs. 20, 21.) 
Shell ovate, thin, compressed, covered with a thin, light yel- 
lowish-brown cuticula; umbones small, papilliform, smooth, behind 
the middle. Sculpture: close concentric, somewhat irregular striae. 
Colour grayish-white with fine white stripes radiating over the 
whole Shell. Interior smooth, white 
with the radiating stripes shining 
through; margins smooth, thin. 
Mantie line entire; adductor scars 
subequal, (the anterior a little long¬ 
er), ovate. Hinge with one large 
projecting (lateral) tooth in each 
valve, the left one crest-like, and 
an indistinct knob-like posterior 
lateral behind the perpendicular ligament lodged in a deep hole 
under the umbones. Dimensions: L. 5.2, h. 4.2, crass. 1.9 mm. 
— Locality: North Island: 5, several sps. 
The animal (text-fig. 21) has a long pedal slit of the mantie, 
behind that a long suture and then a single opening without si- 
phons. Here in the posterior end the mantie edges are finely 
scalloped by very small distant papillae. There are 2 gilis on each 
side extending far upwards 
to behind the ligament, the 
posterior (outer) one with 
a much reduced direct la¬ 
mella; they are smooth and 
United in their lower ends, 
which are, further, fused 
with the mantie. The inner 
(anterior) giil has its re- 
flected lamella nearly as 
high as the direct one and 
for the greater part connec- 
ted with it. The foot is large, 
compressed, and has a well 
developed byssus groove. 
The heart lies in the up- 
Fig. 21. -Anatomy of Montacuta tellinula n. sp. 
g giil axis: h heart; Z opening of liver duet into 
stomach; n nephridium; r ligament: s suture of 
inantle margins. 
Fig. 20. Hinge of 
Montacuta tellinula n. sp. 
