CATALOGUE OP TUNICATA. 55 



apertures moderately far apart. Apertures slightly projecting, but no 

 well-marked siphons. Posterior end rather narrow. Surface closely 

 covered with fine sand. Length (antero-posterior) 2 cm. , breadth (dorso- 

 ventral) 1-5 cm. 



Test is thin, soft and flexible. 



Mantle thin, moderately muscular about the siphons. 



Branchial sac with 7 folds on each side. Stigmata large and numerous, 

 coiled in large spiral infundibula. 



Tentacles branched, 16, large and small alternately. 



Dorsal tubercle small and simple, U-shaped or elliptical ; with an 

 exceedingly large neural gland which extends forwards to the tubercle. 



Gonads ring-like, one on each side of body. 



Locality. Port Jackson ; about a dozen specimens. 



This species in external appearance (PI. Mol. I., fig. 1) is exceed- 

 ingly like M o Igula Forbes i obtained by the "Challenger" Expedition at 

 Port Jackson in shallow water ; but differs from that species in the 

 structure of the branchial sac (fig. 3) and notably in the condition of the 

 dorsal tubercle and neural (or hypophysial) gland (fig. 4). It also has 

 the test much softer and more flexible than in most Molgulas, a feature 

 which I have indicated by the specific name mollis. The hypophysial 

 gland completely covers the ganglion in some specimens and extends 

 beyond it in every direction. It is composed of a very large number of 

 ovate or short tubular caeca (fig. 4, s.n.gl.) In another specimen 

 examined the horns of the tubercle meet anteriorly, so as to make an 

 elliptical figure. Figure 2 shows the left side of the body after removal 

 of the test. The intestine is long and narrow. The ring-like gonad is 

 placed near the loop. 



I was in hopes when I saw this small Molgula in the collection that 

 I might be able to revive and re-describe one of Macdonald's species of 

 " Casira " ; but I find that this species will not really correspond to any 

 of them in appearance and structure, nor will it agree with Stimpson's 

 description of his Molgula inconspicua. 



Molgula sydneyensis, n. sp., PI. Mol I., figs. 59. 



External appearance. Body roughly circular in outline from the 

 side, but much compressed laterally ; soft and flaccid. Both apertures 

 on the broad anterior end, rather far apart, conspicuous, but not very 

 prominent. Surface covered with very fine silvery sand. Length and 

 breadth each about 2 cm. 



Test very thin, with delicate, slightly-branched hairs. 



Mantle moderately muscular. 



