Family Arachnactid.e. 



Acontiferae in which the fourth couple of protocnemes, counting from the mid-ventral 

 line, form the telocnemes. The second and third couples of protocnemes are sterile. Acontia 

 are borne in larval stages by the fourth protocnemes but never by the second. 



Genus Pachycerianthus Roule. 

 Synonym : Pachycerianthus Roule, 1904. 



Arachnactidse living imbedded in mud or sand and provided with a sheath composed of 

 felted nematocysts and foreign substances. Mesenteries and tentacles usually numerous and the 

 quartette arrangement of the deuterocnemes distinct. Type P . benedeni Roule, 1 904. 



In 1 904 Roule established the genus Pachycerianthus for the reception of a form which 

 had been obtained in the Sea of Japan and which presented the peculiar arrangement of the 

 mesenteries (i. e. the telocnemes were the fourth protocnemes instead of the second) which I have 

 taken as one of the chief characteristics of the family Arachnactidae. Roule does not, however, 

 seem to have fully appreciated the taxonomie importance of his discovery, and the name which 

 he chose for the genus refers merely to a remarkable thickness of the directive mesenteries. 



6. Pachyceriantlius fimbriatus nor. nom. J ). 



Synonomy: Cerianthus elongatus Kwietniewski, 1898. 



Stat. 60. Haingsisi, Samau Island, near Timor. Reef. 1 ex. 



Stat. 172. Gisser Island. Reef. 2 ex. 



Stat. 174. Waru Bay, North coast of Ceram. Reef. 2 ex. 



Stat. 213. Saleyer anchorage. Reef. 2 ex. 



Stat. 220. Pasir Pandjang, west coast of Binongka. Reef. 2 ex. 



Stat. 234. Nalahia Bay, Nusa-Laut. Reef. 3 ex. 



Stat. 296. Noimini, south coast of Timor. Litoral. 1 ex. 



Stat. 301. Pepela Bay, east coast of Rotti Island. Reef. 1 ex. 



Stat. 303. Haingsisi, Samau Island. Reef. 1 ex. 



I have already, in the introductory pages, described many of the structural peculiarities 

 of this species, as well as of that which follows, and it will be unnecessary to do more than 

 briefly summarize these here for the better characterization of the species. 



It may remarked, in the first place, that the majority of the specimens had been preserved 

 in alcohol, with the unfortunate result that the internal organs were greatly macerated, the 

 mesenteries being as a rule so matted together by their craspeda as to render a proper study 

 of their arrangement almost impossible. Two specimens, however, those from Station 172, had 

 been preserved in formalin, and these were found to be in a most excellent state of preservation 

 both for macroscopic and microscopic examination, so that what follows is largely based upon 

 what was found in these individuals, although various points were confirmed, when possible by 

 an examination of others. 



1) For explanation of change of name see foot-note p. 12. 



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