12 PLEUROBRANCHID.E. 



tessellated all over with faint lines, and covered with a few 

 scattered pustules : mantle extending on every side beyond the 

 foot, of a reticulated and apparently porous texture, and 

 occasionally puckered or raised in folds ; it is rather thin on 

 the back and thickened at its edges, which are often wavy and 

 wrinkled ; and it has a small notch on the right-hand side, as 

 in Lamellaria ; the edges of the mantle are irregularly studded 

 with microscopic tubercles : head-veil or hood semicircular, 

 forming a bluntly pointed flap at each side ; it is carried in 

 advance of the foot : head short : mouth round and open : ten- 

 tacles proportionally large, but rather short, diverging at an 

 angle of about 45°, and projecting outwards ; they are half 

 open down the middle ; tips obliquely truncated : eyes black, 

 partly imbedded in the outer integument and not always visible, 

 placed close together on the neck between the tentacles, at their 

 base : foot oblong, expanded towards the sides, and sinuous or 

 wavy at the edges, occupying about half the space of the mouth ; 

 it is squarish or gently curved and double-edged in front, and 

 tapers to a rounded point behind : gill-plume placed in the 

 divisional groove between the mantle and foot, not always 

 protruded, and never beyond the edge of the mantle, composed 

 of about 20 sloping strands or pectinations ; it is in some in- 

 dividuals reddish-brown, and in others of the same colour as 

 the rest of the body: liver brown: ovary creamcolour. L. 1. 



Shell oval with a squarish outline, sometimes oblong, more 

 solid and compact than the last species, glossy and partially 

 iridescent : sculpture, microscopic and close-set longitudinal 

 s trite, which are more conspicuous near the spire, and are in- 

 terrupted by the lines of growth, so as to form a series of short 

 rows ; the lines of growth are irregular and rather numerous, 

 and many specimens have also a slight furrow which runs 

 obliquely from back to front: colour pale reddish-brown or 

 tawny, rarely milk-white : spire extremely small but distinct, 

 twisted sideways, and placed at a short distance from the inner 

 margin at the posterior or smaller end ; it consists of two 

 whorls, the first of which is tubercular and somewhat promi- 

 nent: mouth open throughout; dorsal margin gently curved, 

 flat, slightly reflected, and thickened ; inner margin short ; 

 ventral margin long and nearly straight. L. 06. B. 0-325. 



Habitat : Mostly under stones at low- water mark, 

 but occasionally in the laminarian and coralline zones, 



