678 " THETIS " SCIENTIFIC RESULTS. 



Under low power the polyps present a cliaracfceristic punctate 

 appearance, due to the conspicuous nuclei of the scales. The 

 imbrication is well seen on a profile view of the polyps. Besides 

 the scales there are short stout capstan-like bodies ('066 x '031 ; 

 •042 X -038; "038 x "031), with hardly any definite waist, with a 

 knob at each end, and with about six pointed tubercles on each 

 side of the middle line. They correspond closely to Kolliker's 

 " Sechser." 



The characteristic features of this new species are its dichoto- 

 mous sub-parallel branching, the arrangement of the polyps in 

 two alternating rows on each side of the younger branches, and 

 the combination of superficial ctenoid scales with deeper tuber- 

 culate capstans. 



There are many features in common between this species and 

 two others which have been pi-eviously recorded from Australian 

 seas, but it appears to be quite distinct. To mention only two 

 features, we note that our new species may be readily 

 distinguished from Mopsea dichotoma (Linn6), which has been 

 described in detail by Wright and Studer*, by the quite different 

 spicules ; and from M, encrinula (Lamarck), also described by 

 Wright and Studer^, by the pinnate branching. 



Ehrenberg's Mopsea erythraea^ belongs not to Mopsea but to 

 Wrightella or to Melithaea. 



Pourtales's Mopsea ehurnea'^ had eight spicules ))rojecting from 

 the mouth of the polyps, and cannot be included in this genus. 



MOPSEA WHITELEGGEI, sp. nov. 



(Plate Ixvi., figs. 2 and 3 ; pi. Ixxiii.) 



Stations 10, 40, 44, 48. 



This exceedingly delicate and gi'aceful form is typically plume- 

 like in its mode of growth ; all branching is in one plane. Both 

 the secondary branches, and the main branches from which they 

 spring, bear numerous slender twigs disposed on each side like 

 the barbs of a feather along the shaft. The calcareous nodes give 

 rise to one twig each, on opposite sides of the branch in alter- 

 nate succession. A few of the twigs branch again in the same 

 manner. The average distance between two twigs is 1 mm. 



The largest specimen is 23 cm. high with a span of 17 '5 cm. 

 across its luxuriantly branched upper portion. The basal portion 



* Wright and Studer— Chall. Rep., Zool, xxxi., 1889, p 4l, pi. ix., 

 fig. 10. 



s Wright and Studer — Loc. cit. p. 43, pi. vii., figs. 1, 1 , 1 ; pi. ix., 

 fig. 11. 



* Klunzinger — Korallenthiere des Rothen Meeres, 1887, p 57, pi- vL» 

 :fig. 4, 4a, 4«. 



'' Pour tales— Bull. Mus. Comp. Zool. Harvard, i., 1868, p. 132. 



