DESCRIPTION OF SPECIES 51 



With the present evidence it seems best to recognize S. kuranui and S. arenaceum as separate species, 

 while admitting that they may have to be united if more specimens become available. 

 Distribution. Northern part of North Island, New Zealand. 



Genus Aplidiopsis Lahille, 1890 

 Aplidiopsis discoveryi sp.n. (Text-fig. 8C) 



Holotype. St. 941. Size of colony 1-5 x 1-2 x 07 cm. 



Diagnosis of species. Colony of irregular shape, with several common cloacal openings. Zooids 

 with six pointed oral lobes and a wide simple or toothed atrial languet. About fourteen rows of 

 stigmata; no papillae on transverse bars. Stomach smooth ; intestinal loop not twisted. Post-abdomen 

 arising from abdomen by a narrow pedicel. Testis follicles in an ovoid or elongated mass but not 

 serially arranged; ovary embedded amongst testis follicles. 



Occurrence. St. 941 : North Island, New Zealand, 128 m. 



Colony. The colony is an irregular simple mass, not divided into lobes, and broadly attached to 

 a barnacle shell. The common test is semi-transparent, and, there being no sand on or within the 

 test, the zooids are visible. They are arranged in several small systems each with an oval or slit-like 

 common cloacal opening. 



Zoom (Text-fig. 8C). Zooids vary from 4-5 to 7-5 mm. in total length. The thorax is 2-3 mm. long, 

 slightly wider than the abdomen which measures 1-5-2-5 mm. in length; the post-abdomen is generally 

 at least as long as the abdomen. The size of the post-abdomen, however, varies according to the degree 

 of development of the gonads; it is narrow and attached to the abdomen by a short and slender 

 pedicel. Pigment, which in the preserved state is orange in colour, is present on much of the body wall, 

 especially in the post-abdomen. 



Thorax. The oral siphon has six pointed lobes, and the round atrial opening, which is opposite the 

 first or second row of stigmata, is surmounted by a fairly wide simple or distally toothed languet (a.L). 

 Eight to ten narrow longitudinal muscles run down each side of the thorax. At the posterior end of 

 the thorax the muscles condense to form a single band on each side, and the left band passes over to 

 the right ventral side of the abdomen where it unites with the right band. The single muscle (mus.) 

 thus formed continues into the post-abdomen and ends at its posterior end. 



Fourteen or fifteen rows of stigmata are present, each with fifteen to twenty stigmata. The trans- 

 verse bars bear the pointed triangular dorsal languets, but no papillae. 



Gut. The oesophagus is quite long and narrow, and enters the stomach on its oblique antero- 

 dorsal face. The stomach is ovoid, with the anterior end generally wider than the posterior. Two short 

 narrow chambers constitute the post-stomach. The intestine makes a simple loop. The rectum extends 

 to the level of the 10th row of stigmata and ends in a two-lipped anus (a). 



Gonads. Much of the post-abdomen is occupied by the bulky testis (t) composed of numerous 

 pear-shaped follicles. The follicles, instead of being serially arranged as in Aplidium, are grouped 

 into an ovoid or somewhat elongated mass as in Polyclinum. As in that genus also, the ovary (ov.) is 

 a small body embedded amongst the testis follicles. Neither sperm duct nor oviduct could be dis- 

 tinguished in the ' Discovery ' specimen. 



Remarks. No other species of Aplidiopsis is known from New Zealand. A. discoveryi is not likely 

 to be confused with any other species hitherto described. 



Distribution. North end of North Island, New Zealand. 



7-2 



