3 6 ° 
MOLLUSCS. 
example of the Pellibranchs. It is slug-like in form, but without any tentacles. 
The species figured ( L. capitata ) is a minute animal, about a sixth of an inch in length, 
chiefly of a black colour, but occasionally somewhat transparent and colourless. 
Alder writes that “ this curious little animal is probably pretty generally diffused, 
but on account of its minute size it may readily be overlooked. It is gregarious; 
and, wherever met with, it has usually been found in abundance, appearing when 
contracted like little black dots scattered over the conferva on which it feeds.” 
Limapontia capitata (much magnified). 
It lives between tide-marks, feeding upon small algae, and deposits its ova in small 
pear-shaped capsules, each containing about one hundred eggs. 
The only form belonging to this group, the position of which is 
not settled, is the parasitic genus Entoconcha. The animal is worm- 
like and spirally coiled, and attaches itself by the oral end (a) to one of the 
blood-vessels ( E ), within the visceral cavity of a certain group of Echinoderms. 
One species is found in Syncipta, and a second ( E. muelleri) occurs in the 
trepang ( Holothuria ) of the China Sea. In the very early or larval state Ento¬ 
concha is contained in a minute operculated glassy shell. The subsequent changes 
between this and the perfect condition have not yet been observed. It is the 
lowest type of Nudibranchiata, if indeed it really belongs to that suborder, which 
is not absolutely certain, some authors even locating it near Eatica. Were it not 
for the form of the larva, one would hardly have supposed that this worm-like 
creature belonged to the Mollusca at all. It has neither jaw nor radula, but the 
mouth is adapted for sucking. The sexes, as in the typical Nudibranchs, are 
united in the same individual. The female element (b) is somewhat anterior, the 
male organ (c) being at the opposite extremity. The central portion of the animal 
serves for a certain time as a nursing-pouch for the embryos, which subsequently 
are extruded at an opening at the posterior end. Only one out of every hundred 
or two hundred specimens of Synajda is infested with the Entoconcha. Pelseneer 
locates it next to Eidinia among the Pectinibranchs. 
Covered-Gill Subgroup,— Suborder Tectibranchiata. 
This constitutes the second suborder of Opisthobranchiata, and includes 
certain molluscs characterised by the possession of a lateral gill, protected bj r 
the mantle, or a shell. The members of the group are hermaphrodite animals, 
and differ from the Nudibranchs, not only in their respiratory organs, but 
also in the possession of a true mantle, which, in the Nudibranchs, is repre¬ 
sented by the dorsal shield. On the other hand, they show affinity with certain 
