Hicksonella, a New Gorgonellid Genus. By J. J. Simpson. 683 



The ccenenchyma is very thin and densely spiculose ; when 

 dry it is extremely brittle. 



The canal system is difficult to determine owing to the thin- 

 ness of the ccenenchyma. It was found impossible to detach a 

 portion of the ccenenchyma from the axis without damaging the 

 canals. Serial sections were made from a decalcified portion of 

 the ccenenchyma, but the results were not very satisfactory. The 

 furrows on the axis suggest a concentric series of canals separating 

 the ccenenchyma from the axis, but it is very doubtful whether 

 one or more of these is larger than the others, and the possession 

 of an outer series of canals is quite uncertain. 



From end to end of the colony there is a narrow streak devoid 

 of polyps, which participates in the spiral arrangement of the 

 colony (pi. XIII. fig. 1). It occupies between one-fourth and one- 

 third of the circumference of the ccenenchyma. The remaining 

 three-fourths to two-thirds is densely covered with small elongated 

 verruca?. In the smaller specimen the basal portion, for a distance 

 of 8 cm., is devoid of polyps. 



The verruca? are long and club-shaped, and somewhat resemble 

 those of Scirpearia Jiagellum ; the terminal part is considerably 

 enlarged. They are about 1 ' 5 mm. in length, and about ' 5 mm. 

 in diameter at the widest part. They are very spiculose, and the 

 surface, when viewed with a lens, reveals a series of minute hori- 

 zontal, overlapping scales, which recalls the armature of a 

 Caligorgid. 



At the utmost they are only feebly retractile into the ccenen- 

 chyma, but their enormous size, the thinness of the ccenenchyma 

 and their dense armature, would seem to preclude the possibility 

 of any great degree of retraction. 



When the tentacles are inturned there is a distinct eight-rayed 

 figure at the summit of the verrucas, and the scales on the aboral 

 surface of the tentacles form a sort of pseudo-operculum. Further 

 retraction of the tentacles results in a very definite horizontal 

 wrinkling of the verruca?. 



The verruca? are very densely packed on the polyp-bearing 

 region, and about a dozen occur on one transverse line. 



Young polyps occur scattered among the older ones, and so 

 render any definite arrangement impossible. 



In the larger specimen the colour of the ccenenchyma in the 

 bare tract is a dark brick -red, but the verruca? are creamy white 

 with an occasional trace of an orange tint. In the smaller specimen 

 the bare tract is also reddish-orange, but the polyps are pinkish- 

 purple. 



The spicules of this species are extremely characteristic, but 

 very diverse in form and irregular in outline. 



The figs. 2 a, b and 3 a, b, show some of the more definite 

 types. 



2 z 2 



