6 Memoirs of the Indian Museum. [Vor vale 
retracted. The number of lobes at the apertures, which is as usual six for the branchial 
and four for the atrial, is always discernible, though very faintly, from the outside. 
The surface is entirely covered with a layer of fine sand attached to the hair- 
like processes of the test. The sandy coating is partly continued on the siphons, 
thus rendering them incapable of being completely retracted. The colour of the 
sand is dark greenish grey. 
Size: length of the body (dorso-ventral) 28 mm., breadth of the body (antero- 
posterior) 21 mm., distance between the apertures 7 mm. | 
The Test is thin (less than o°2 mm. in thickness), membranous but rather 
tough, and is quite transparent. It bears fine, branched, hair-like processes all over 
the outer surface, to which sand is attached in such quantity as to form a solid 
coating of uniform thickness (about 0°5 mm). On sections it is clearly seen that the 
sand grains are also attached to the outer surface of the test itself, but are never 
imbedded in the substance of the test. The length of the hair-like processes does 
not exceed I mm. 
The internal body taken out of the test has nearly the same form as the entire 
animal (Pl. II, figs. 3 and 4), the test being in close contact with the mantle all over. 
The test can, however, be separated with ease except at the tips of the siphons 
where it is firmly attached to the mantle. The siphons, though short, are promin- 
ent, and the lobes at the branchial and atrial apertures are very distinctly seen. 
Most of the internal organs, particularly the gonads, the intestine, and the endostyle 
show through the mantle. The internal body is of a pale brownish-grey colour with 
a slight tinge of greenish-yellow. | 
The Mantle is thin, membranous, and for the most part transparent. The 
musculature is not strong; in the anterior part of the body stout longitudinal bands 
radiating from the bases of the siphons are conspicuous, but in the posterior half 
there are scarcely any muscle bands visible to the naked eye. Examined under a 
low power, however, we find minute spindle-shaped muscle bands, so characteristic 
of the Molgulidae, scattered over the whole extent of the mantle. They are very 
minute and run in all directions, not forming a continuous layer. In the anterior 
part of the body they lie mostly in a transverse direction so as to cut the con- 
spicuous longitudinal bands at right angles. Ring muscle fibres are well developed 
on the siphons, especially at their base, and form powerful sphincters. 
The Tentacles are compound, and much branched; there are about seven large 
and seven small ones placed alternately. The larger tentacles show ramifications 
repeated to the fifth order. The stem is pyramidal and curved so as to have the 
convex side looking posteriorly. The fine terminal twigs end rather bluntly, with the 
epithelial lining somewhat thicker at the tip than elsewhere. 
The Branchial Sac is moderately strong, with seven distinct but narrow folds on 
each side. There are usually three or four internal longitudinal bars upon each fold, 
and none in the space between two folds. The transverse vessels are very irregular ; 
they originate at the base of the folds and soon divide and anastomose to form a 
network in the meshes of which the infundibula are placed. Narrow, delicate mem- 
