Trididemnum hians

Stations. SB 3; SR 8; SS 1; SS 3; SS 4; SS 5; SR 14; SS 11; SC 6; SC 12; SR 23; CP 4383. The colonies are grey in formalin as the zooids contain abundant mud seen through the transparent tunic. They form soft crusts with sparse spicules in patches between groups of zooids. The oral siphon has 6 lobes, the atrial tube is always contracted. The thorax has some brown pigment in the body wall and an anterior black spot. Twelve stigmata were counted in the first half branchial row. The single testis lobe is covered by 8 to 9 turns of the sperm duct. A single oocyte is present with the testis in the intestinal loop (Fig. 5 D). The larval trunk is 1 mm long, the tail hardly reaches a half turn around it (Fig. 5 A, B, C). There are 3 divergent adhesive papillae generally lined by 6 ampullae on one side and 5 on the other side. Thorax and abdomen are already differentiated in these large larvae which have no bud. The spicules up to 50 µm in diameter for the largest are composed of numerous blunt rays. The specimens from Guiana have been compared to the type material from Guadeloupe. They are recorded here for the first time in another location.