52 DISCOVERY REPORTS 



Genus Protopolyclinum gen.n. 

 Diagnosis of the genus. A genus of the family Polyclinidae with the atrial siphon opening directly 

 on the surface of the colony, not into a common cloacal cavity ; the zooids divided into thorax, abdomen 

 and post-abdomen, the post-abdomen joined to the abdomen by a narrow neck, and containing the 

 gonads and heart, and having muscles in its body wall; the branchial sac with papillae on the trans- 

 verse bars, and the intestine not twisted as in Polyclinum. 



Protopolyclinum pedunculatum gen.n., sp.n. (Text-fig. 9, PI. I, fig. 10) 



Holotype. Size: stalk, 12-6 cm.; head, 1-4 cm. 

 Occurrence. St. 934 : North Island, New Zealand, 92-98 m. 



Colony (PL I, fig. 10). There are four specimens, measuring, including the stalk, 10, 12, 13 and 

 14 cm. The heads have respectively the following measurements: 



Length (mm.) 6, 10, 14, 14 



Greatest diameter (mm.) 5, 7, 10, 10 



The head of the colony is ovoid, and usually slightly narrower towards the point where it joins the 

 stalk. In the preserved state it is pale yellow grey, and of a soft consistency. In most of the specimens 

 the stalk is widest at its junction with the head, but in the two smallest colonies the greatest width is a 

 little way below the head. The lower half or quarter of the stalk becomes gradually narrower, so that 

 near the point of attachment it has a diameter of only 1 mm. At its widest it may reach a diameter of 

 4 mm. Immediately below the narrowest part, the stalk expands to form a wider base by which the 

 colony is attached to the substratum. The two smallest heads arise from a single expanded basal mass 

 of test and, although the other two are separate, it is possible that originally all four specimens were 

 members of a single complex colony. The stalk is firmer than the head, especially in its lower half. In 

 its upper part it has the same colour as the head, but the lower part becomes gradually darker and more 

 orange coloured. A series of dark rings round the stalk gives it an annulated appearance. 



The zooids are not arranged in systems, and have no apparent order in the head. 



Zoom (Text-fig. 9). The zooid is divided into thorax, abdomen and post-abdomen. In a specimen 

 of average size these measure respectively about 27, 2-0 and 4-0 mm. ; these lengths do not include the 

 long post-abdominal process which extends for several centimetres down inside the stalk. 



Thorax. The thorax is wider than the other two divisions of the zooid. The oral (o.s.) and atrial 

 (a.s.) siphons are both short and wide, and show no lobes or only very shallow ones. The siphons are 

 placed close together at the anterior end of the thorax. The atrial siphon opens directly on the surface 

 of the colony and not into a common cloacal cavity as in other members of the family Polyclinidae. 

 On each side of the thorax there are about six longitudinal muscles, divided into a few branches at 

 their upper end, and converging as they approach the abdomen. Longitudinal muscles are present 

 not only on the abdomen, but also down the whole length of the post-abdominal process. There are 

 about twelve simple oral tentacles arranged in a single circle at the base of the siphon. The dorsal 

 tubercle is a small ovoid body, with a simple longitudinal slit. The branchial sac has about thirteen 

 rows of stigmata which are rather wide and rectangular and number about sixteen in a row. On the 

 transverse bars of the branchial sac there are small papillae similar to those in the genus Polyclinum. 

 The dorsal languets are short and curved. 



Gut. The oesophagus is of moderate length and width. The stomach is wide and roughly barrel- 

 shaped, with the walls almost smooth, but showing large, faint areolations or ovoid markings. In 

 some zooids these are outlined by little more than slight irregular transverse ridges. The post-stomach 



