POMATOCERUS TRIQUETER. 365 
1890. Pomatoceros triquetroides, Malaquin. Annél. Boulon., p. 49. 
1891. Pomatocerus triqueter, Hornell. Trans. Biol. Soc. L’pool, vol. v, p. 264. 
1893. Pomatoceros triquetroides, D. Ch., Lo Bianco. Atti R. Accad. Se. Nap., vol. v, no. 11, p. 86. 
»  Pomatocerus triqueter, Levinsen. ‘‘ Hauchs.” Tog., p. 354. 
1894. Pomatoceros 3 De St. Joseph. Ann. Sc. nat. 7° sér., xvii, p. 353, pl. xi, 
figs. 393-407. 
»,  Pomatocerus 5 Bidenkap. Christ. vid.-selsk. Forhandl., p. 138. 
1896. 3 "5 Appellof. Bergens Mus. Aarb., xiii, p. 12. 
1897. a 5 Michaelson. Polych. deutsch. Meere., p. 188. 
1898. i a Lénnberg. Meddel. f. Kong]. Landtbr., St. no. 1, aar. 1898 (fide auct.). 
1904. <3 5 Journ. M. B. A., vol. vil, p. 232. 
1907. Pomatoceros 5 Soulier. Acad. Sc. Montpell., p. 138. 
1909. Pomatocerus . Fauvel. Bull. Inst. Oceanogr., No. 142, p. 66. 
Lo Bianco. Mitt. Zool. Stat. Neap., Bd. xix, p. 584. 
Fauvel. Ann. Sc. nat., 9° sér., t. x, p. 210. 
bP) 3) ” 
1910. 3 a Southern. Proc. Roy. Irish Acad., vol. xxviu, p. 242. 
a _ Elwes. Journ. M. B. A., vol. ix, p. 66. 
1911. . es Fauvel. Bull. Inst. Oceanogr., No. 194, p. 39. 
3 v5 re Ditlevsen. Danmark-Eksped. Groul., Bd. v, p. 430. 
$s s 3 Riddell. Proc. Liverp. Biol. Assoc., vol. xxv, p. 65. 
1912. 55 33 Crawshay. Journ. M. B. A., vol. ix, p. 347. 
Wollebek. Skrift. selsk. Krist., Bd. ii, No. 18, p. 114, pl. xlii, figs. 1—6, 
and pl. xlix. 
1913. | ‘ Giard. (iuvres Div., p. 57. 
»  Pomatoceros a5 Stephenson. ‘Trans. Roy. Soc. Hdin., vol. xlix, p. 808. 
1914. i A Southern. Proc. Roy. Irish Acad., No. 47, p. 147. 
re - A Fauvel. Campag. Scient. Monaco, Fasc. xlvi, p. 347. 
1915. Pomatocerus s Allen. Journ. M. B. A., vol. x, p. 644. 
» Pomatoceros i Southern. Irish Sc. Invest., No. 3, p. 49. 
1920. is 5 Eliason. Polych. Oresund, p. 79. 
Habitat—Abundant on most shores of the British Islands, occurring both between 
tide-marks on stones and rocks, on shells in the laminarian zone and deeper water beyond, 
often in company with Hydroides norvegica. 
Dublin Bay and West Coast of Ireland (Southern); Forth (Cunningham and Ramage); 
Plymouth (Spence Bate and B. Rowe, Allen, Crawshay) ; Torquay (Elwes). 
It extends to Greenland (Ditlevsen), Iceland (Leuckart), Finmark (Norman), Spain 
(Rioja), Mediterranean (Delle Chiaje, Grube, Philippi), shores of France (De Quatrefages, 
De St. Joseph, Fauvel, etc.). 
The dorsal part of the collar forms a great free lamella, which, probably by accident, 
is sometimes separated from the rest of the collar, and its edges are laciniated, though normally 
it seems to be smooth. The collar continues to the ventral surface as a broad membrane 
usually thrown into folds in the preparations. De St. Joseph considers the separate parts 
of the collar dorsally are normal (Plate CX VII, fig. 1). 
The branchize are somewhat short, and arranged in two lateral fans of thirteen or 
fourteen to twenty (De St. Joseph) filaments, each of which is tapered from base to apex, 
where it is terminated by a subulate process of some length (Plate CX XII, fig. 2). The pinnee 
