8 THE VOYAGE OF H.M.S. CHALLENGEK. 



63. Myzostoma cysticolum, Graif. 



Myzostoma cysticolum, Graff, Bull. Mus. Comp. Zool. Cambridge, vol. xi. p. 132, 1883. 



65. Mijzostoma willemoesii, Graff (PI. III. figs. 5, 6). 



The collection before me includes a deformed fragment of arm, and a deformed pinmde 

 of Antedon Jlexilis, P. H. C, from Station 192, Challenger Expedition, in the Arafura Sea. 

 The former contains a hermaphrodite Myzostoma which I regard as new, and which is 

 described below as Myzostotna heardi (No. 77); while the pinnule deformity arises from 

 the presence of Myzostoma ivillemoesii. 



The deformity has a close resemblance to those represented on pi. xiv. of the Eeport. 

 The segments are broadened, shaped like a roof, and united into a capsule which encloses 

 the roof-shaped widened ambulacral groove. But while in the former the whole pinnule 

 shares in the deformity, the point of the pinnule (a) remains in this case unchanged and 

 free. And while formerly I always found (Report, p. 71) in each deformity a pair of Myzo- 

 stomata — a larger female and a dwarf malC' — the present deformity contains only a single 

 male. This measures 1'4 mm, in length, and 1 mm. in maximum breadth. It corresponds 

 with that figured in the Report, pi. xiv. fig. 5, except that the suckers are less con- 

 spicuous, being only partially recognisable with the lens, and that the ten cirri are very 

 irregularly developed. In the former the cirri were not indeed of equal length, but in the 

 specimen before me the differences are much more striking, and the length varies from 

 0'03 to 0'13 mm., as can be distinctly seen by an inspection of fig. 6 where the- cirri 

 (III-VII) of the left margin are represented. After saturation with glycerine it was 

 seen that the restricted stomach branches leave a free marginal zone, O'l mm in breadth. 



66. Myzostoma inflato7\ Graff. 



Myzostoma infiator, GrafF, Bull. Mus. Comp. Zoiil. Cambridge, vol xi. p. 133, 1883. 



67. Myzostoma murrayi, Graff. 



Myzostoma murrayi, Graff, Fhid. 



68. Stelechopus hyocrini, Graff. 



The host of this species is Hyocrinus bethellianus, Wyv. Thompson. 



