. ' 



4 8 



One of the principal arguments relied on by Braem is the occurrence of V. continentalis 

 in Lake Issyk-Kul, a sheet of water which lies at a high level far in the interior of Asia. But 

 when it is remembered that I'. bengalensis gives rise to resting buds, it is not very unsafe 

 to suppose that these might be carried from one place to another, on the feet or beaks of 

 migratory birds, without losing their power of germination ; and that very long intervals might 

 be bridged over in this way. 



Whatever view is adopted with regard to this point, it is interesting to find a marine 

 species of Victorella in a locality which may be regarded as central with reference to the Indian 

 Coast and Lake Tanganyika, two of the localities from which species of the genus have been 

 recorded. This fact becomes even more significant when taken in conjunction with the occurrence, 

 recorded below, in the Malay Archipelago of a species of Arachnoidea which appears to be 

 closely related to A. ray-lankesteri of Lake Tanganyika. 



Fam. 2. Arachnidiidae Hincks. 



Arachnidiidac Hincks, 1SS0, ''Hist. Brit. Mar. Pol.", p. 508. 



Hislopiidae (pars), Annandale, 191 1, "Syst. Notes Cten. Pol.", Ree. Ind. Mus. VI, p. 197. 



Zoarium adnate, branching typically in a cruciform manner, though frequently showing 

 some irregularity in this respect. Zooecia consisting of a narrow proximal part, often much 

 elongated, and of a much dilated distal part. Orifice subterminal, on a low papilla or a much 

 elongated peristome r ). Genera, Arachnidium^ Arachnoidea. 



Arachnidium Hincks. 



Araclinidia Hincks, 1859, Rep. 28* Meeting Brit. Ass., Leeds, 1858, Notices and Abstr., p. 128. 

 Aracluüdia Hincks, 1859, Quart. J. Mier. Sci., VII, p. 131. 

 Araclinidia Hincks, 1862, Ann. Mag. Nat. Hist. (3) IX, p. 471. 

 Arachnidium Hincks, 1S77, Ann. Mag. Nat. Hist. (4) XX, p. 216. 

 Arachnidium Hincks, 1880, "Hist. Brit. Mar. Pol.", p. 508. 



The first notice cited above mentions the description of "a new genene type, Araclinidia 

 " Hippothboides, a delicate Ctenostomatous Polyzoon, curiously resembling in general appearance 

 "the well-known Hippothod" . The second is a copy, not literally exact, of the first. A formal 

 diagnosis was published in the 1862 paper; but the information given in the 1859 notices is 

 probably sufficiënt to justify this year as the date of the introduction of the genus. 



In 1877 Hincks uses the form Arachnidium, giving the derivation as "dim. of cï.puyyiov, 

 a spider's web", and stating that the name "Araclinidia" had been given "wrongly". I believe 

 that the amended form has been employed in practically all later accounts of the genus, and it 

 seems to me desirable to decide that the original name should be regarded as a lapsus ca/aun\ 

 and that it may therefore be replaced by the correct form Arachnidium, in accordance with 



1) I usc the term "peristome" as the equivalent of the free, terminal jiortion of the zooecium, hearing the orifice, without 

 implying that it is the morphological equivalent of the parts so designateil in Cyclostomata and Cheilostomata. 



48 



