i; Knurr on the tunicata 173 



shell fragments. The shape also is peculiar. It is much elongated dorso-ventrally, and 



is depressed so as to form a transversely elongated sausage-shaped body. 



The test also is like that of most species of Molgula, in being prolonged into branched 

 hair-like processes, to which the sand is attached. The branchial sac is strong, on account 

 of the presence of numerous very wide internal longitudinal liars (PI. XXII. figs. 6 

 and 7, i.h). Most of the transverse vessels are very narrow, but occasionally one meets 

 with one which is considerably wider. The meshes in the interspaces are transversely 

 elongated, and contain each about a dozen rather narrow stigmata. The whole branchial 

 sac, and the numerous tentacles, are of a dark brown colour. 



The polycarps only project slightly, as they are imbedded in the thick mantle. 



Two specimens of this curious species were dredged off East Moncceur Island in Bass 

 Strait, at Station 162 ; April 2, 1874 ; depth, 38 to 40 fathoms ; bottom, sand. 



Pohjcarpa quadrata, Herdman (PI. XXII. figs. 8-10). 



Polycarpa quadrata, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 78. 



External Appearance. — The body is oblong or oval in shape, erect and somewhat 

 compressed laterally ; both ends are broad and rounded, and the dorsal and ventral edges 

 are nearly straight and parallel. The body is attached chiefly by the posterior end. The 

 branchial aperture is terminal, sessile, inconspicuous and minute, the atrial is on the 

 dorsal edge, more than one-third of the way from the anterior to the posterior end, it 

 also is minute and inconspicuous. 



The surface is considerably creased in all directions, especially round the apertures. 

 The colour is dirty white. 



Length of the body, 2 cm.; breadth of the body, 1"6 cm. 



The Test is not thick, it is tough and strong, but not stiff, and is white and glistening 

 on the inner surface. 



The Mantle is very thin, and adheres closely to the test. 



The Branchial Sac has four slight folds upon each side, and in these places the in- 

 ternal longitudinal bars are very numerous and close. The meshes are elongated antero- 

 posteriorly, and are usually divided by a narrow transverse membrane, and each contains 

 from one to four stigmata. 



The Dorsal Lamina is a plain membrane. 



TJie Tentacles are simple. 



The Dorsal Tubercle is ovate in outline ; it is very minute, and is placed at the 

 posterior end of a deep peritubercular area. 



This species has the typical Cynthiad appearance (PL XXI 1. fig. 8). The test is thick 

 but tough, is not covered with sand, and is of a dirty white colour. The apertures are 

 minute, and are both cross-slit (see atrial aperture in PI. XXII. fig. 8). 



