NARRATIVE OF THE CRUISE. 



317 



Pentacrinus alter nici 'mis, P. H. C. ; whereas the pinnules of Antedon basicurva and 

 Antedon incequalis, P. H. O, become swollen and spirally coiled owing to the presence of 

 Myzostoma willemoesii (fig. 127d), forming thus a central cavity in which the parasites 

 arc found. The pear-shaped swellings of the pinnules of Pentacrinus alternicirrvs, 

 P. H. C. (fig. 127b), caused by the presence of Myzostoma deformator, are no less 

 remarkable. 



" Many Crinoids are liable to the attacks of several distinct species of Myzostoma. ; 

 Pentacrinus alternicirrus, P. H. C, for example, harbours an ectoparasitic species besides 

 the three endoparasitic Myzostomida just mentioned ; similarly, Antedon triquetra, 

 Semper MS., is infested by no less than six ectoparasitic forms. On the other hand a 

 given species of Myzostoma is by no means always confined, to the same host ; many 



Fro. 127. — Malformations upon Crinoids caused by Myzostomida ; all magnified about 5 diameters. 



A, Arm swelling of Pentacrinus alternicinus, P. H. C, inhabited by Myzostoma penlacrini. B, swollen pinnule of the same, 

 inhabited by Myzostoma deformator; C, arm swelling of Antedon incequalis, P. H. C, inhabited by Myzostoma lenui- 

 spinum ; D, malformed pinnule of the same, inhabited by Myzostoma willemoesii; E, cyst on thedisk of A ntedou radiospina, 

 P. H. C. , inhabited by Myzostoma murrayi, 



indeed are found upon two, three, or even four distinct species of Crinoids. .The 

 only genera of Crinoids upon which Myzostomida have been found are Antedon, 

 Actinometra, Pentacrinus, Bathycrinus, Metacrinus, and Hyocrinus. 



" The presence of malformations upon many fossil Crinoids 1 indicates that in the 

 earlier periods of the earth's history as well as now these parasites existed." 



The Crozet Islands. 



On the 31st December, at 1.30 A.M., the vessel tacked and stood off Hog Island under 

 easy sail until daylight. At 3.30 a.m. she tacked again and stood towards the land, but the 

 weather becoming thick, at 6 a.m. again stood off under topsails and jib. Shortly after 

 noon the fog lifted a little and sail was made, and the island was sighted again at 3 p.m., but 



] See Zool. Chall. Exp., part xxvii. p. 2, 1884. 



