OUR KNOWLEDGE OF NEW ZEALAND HOLOTHURIANS. 113 



Mr. Henry Suter in 1896, at the same time as the original specimen o£ 

 Rhabdomolgus novce-zealandm. The specimen was slightly damaged, about 

 2*5 cms. in length and about 0*15 cm. in transverse diameter in the middle. 

 When it first came into our hands it was of a very pale pinkish colour, nearly 

 white, and opaque, the opacity being probably due to the alcohol in which it 

 was preserved. 



The tentacles are ten in number, pinnately branched, each with about five 

 branches on each side increasing in length towards the distal end of the 

 tentacle. The calcareous ring is feebly developed and composed of 

 numerous small pieces, the arrangement of which could not be satisfactorily 

 made out. The internal anatomy, so far as determinable, is typical. 



The integument bears numerous scattered sense-papillse as in Rliabdoinolgus 

 novce-zealandm. It contains no wheels but fairly numerous scattered, slender, 

 contort, sigmoid spicules, about 0"05 mm. in length, which as a general rule 

 have sharply and gradually pointed ends (fig. 30 a). The spicules appear to be 

 confined to the anterior portion of the body, where they are uniformly 

 scattered over the inter-radii, leaving a narrow band opposite the middle 

 of each longitudinal muscle quite free from them. The most remarkable 

 feature about them is their apparently constant arrangement in pairs 

 (figs. ?>0h, 30 c), the two individuals of each pair lying parallel with one 

 another and so close together as frequently to appear as a single spicule. In 

 each pair the curvature of the two sigmata appears to be identical, and in the 

 case of the larger ones the two components of the pair actually appear to have 

 fused together by concrescence throughout the greater part of their length, 

 remaining separate only at the two extremities (fig. 30 c). We believe that 

 this curious arrangement of the sigmata in pairs is unique ; but in Chirodota 

 japonica, which is perhaps the most closely related species, they are arranged 

 in radiate groups of from three to nine *. 



Like Chirodota japonica, our species would fall under Studer^s proposed 

 genus Sigmodota, characterized by the presence of sigmoid spicules without 

 wheels ; this genus has, however, been abandoned by recent authors. The 

 reduction of the spiculation in " Sigmodota," and especially the absence of 

 spicules from the hinder part of the body of our species, seem to indicate 

 the probability that the species of Rliahdomolgus are simply Cliirodotas which 

 have progressed still further in this direction and completely lost their 

 spicules. 



Rhabdomolgus nov^-zealandi^, sp. n, (Plate 11. figs. 1-1 ; Plate 13. 

 figs. 16-17 ; Plate 14. figs. 22-29.) 



The history of this species has already been briefly referred to in our 

 introductory remarks. It first became known through the discovery of a 



* Vide Theel, ' Challenger ' Reports, vol. xiv. Hulothurioidea, p. 17. 



