72 AMERICAN HYDROIDS. 



Sertiilftrid argentea ALDER, Cat. Zooph. Northurnb., 1857, p. 26. 



iiriji-iili-ii A. A<;.\ssiz, North American Acalephte, 1865, p. 144. 



urgi'iiti'ii VAN BEXEDEN, Fauna Littnrale de Belgiqne, I860, p. 1S4. 

 i-in di-iji'iiti'd HIXCKS, British Hydroid Zoophytes, 18138, p. 268. 



diyi-iilei.i VERRILL, Invert. Vineyard Sound, 1871-T2, p. 732. 

 Sertularid urgentea SCHULZE, Nordsee Exped., 1872, p. 132. 



Si'i-tnldi-id nfijenten VERRILI., Proc. Am. Assn. Adv. Sci., 1873, pp. 256, 359, 304, 374. 

 K-i-fitlarln in-genti'ii MclNTOSH, Ann. and Mag., 4th ser., XIII, 1874, p 213. 

 Ki-rliildriit drgenlca VERRILL, Amer. Journ. Sci., VII, 1874, p. 39. 

 Mvtitlitrid di'i/i'iitfd VERRILL, Amer. Journ. Sci , VII, 1874, p. 133. 



urgentea CLARK, Hydroids of Pacific Coast, 1876, p. 257. 



iiryentea, var. diraricata CLARK, Hydroids of New Eng. Coast, 1876, p. 64. 

 Srrttittirid tirgcuten MERESCHKOWSKY, Ann. and Mag., 5th ser., I, 1878, p. 324. 

 SiThilnrid dnji'iitt'd WIXTIIER, Naturhist. Tidsskrift, 1880, p. 249. 

 '.' Xi-rliildi-in argenlea BERGH, Goplepolyper fra Kara Havet, 1887, p. 335. 

 Sertuliii-ia argenlca BOURNE, Hydroids of Plymoutli, 1889, p. 396. 

 di-id nrt/t'nted DRIESCH, Tektonische Studien, 1890, p. 206. 

 -iii iir/jcnti'ti MAKKTANNKK-TI-RNERETSCHER, Hydroiden des k. k. Naturhist. Hofimiseums, 1890, p. 232. 



driji'nli'd LEVINSEN, Vid. Udb., "Hauchs" Togter, 1893, p. 370. 

 Sertuldrid in-iji'nli-n CRAWFORD, Ann. and Mag., 6th ser., XVI, 1895, p. 261. 

 Tlinldfid nfiji iitui I'XIXNEVIE, Norwegian North Atlantic Exped., 1899, p. 83. 

 Tlntiiirid di-i/fiitfd XCTTING, Hydroids from Alaska and Puget Sound, 1899, p. 741. 

 Tltuiurid di-i/i'nli'd NUTTING, Hydroids of Woods Hole, 1901, p. 363. 

 Sertuhiria argentea HARGITT, Amer. Naturalist, 1901, p. 390. 

 Tliuiaria argenten NUTTING, Hydroids of the Harriman Exped., 1901, p. 184. 

 Thuiaria argentea WHITEAVES, Cat. Marine Invert. Eastern Canada, 1901, p. 27. 

 Srrtnldri/i r</i -ntfd S.KMUNDSSON, Bidrag til Kundskaben islandske Hydroider, 1902, p. 62. 

 i ur/ii'iitca TORREY, Hydroids of Pacific Coast, 1902. p. 67. 



. Colon} 1 attaining a height of a foot or more, usually considerably less. Stems 

 growing often in clusters, long, slender, divided by distant nodes into irregular iiiternode.s, with 

 distant hydrothecse. Branches rather distant, spirally arranged, each branch dividing dichoto- 

 mously into an exceedingly delicate and graceful tracery of branchlets, the whole colony being 

 among the most beautiful of the hydroids. The axil of each branch and branchlet is occupied by 

 a liydrotheca. Internodes distant and irregular. Hydrotheca 1 subopposite to alternate, not 

 greatly immersed, the terminal one-third often being free, bending gracefully outward, with a 

 strongly bilabiate aperture, one tooth being usually much longer and more acute than the other. 

 Operculum two-valved. 



Gonosome. Gonangia borne on upper sides of branches at bases of hydrotheca', subtriangu- 

 lar in outline, being widened distally by two blunt lateral spines. Aperture terminal, collar very 

 low, acrocysts borne on mature gonangia. 



Distribution. One of the commonest species in shallow water on both shores of the North 

 Atlantic, Alaska, and the North Polar regions. 



This is one of the best known of the Sertularidtfi. It most nearty resembles T. cupressina, 

 from which it differs in having a much more bushy habit, more exserted hydrothecse with more 

 conspicuous teeth. The gonangia are broader in proportion to their height, and the lateral 

 spines are usually less conspicuous. The finest specimens I have seen came from Jerome Creek, 

 Maryland. 



THUIARIA CUPRESSINA (Linnaeus). 

 (Plate XIII, figs. 1-3.) 



fiea-ci/press ELLIS, Essay Nat. Hist Corallines, 1755, p. 7. 

 Si'rtiilitriii 1'iijii-i-KniiKi LINN.EUS, Systenia Naturif, 1758, p. 808. 



rn iirrsxi mi IIurTTUYN, Natuurlyke Historic, XVII, 1761-73, p. 537. 

 iilaria cupressina (part) PALLAS, Elenchus Zoophytorum, 17611, p. 141. 

 dldi-id /iijiirx.fi/iii (part) LINN.EUS, Systema Natunu, 1767, j>. 1308. 



rii/ii-i:xniiid (part) BODDAERT, Lyst der Plant-Dieren, 1768, \>. 176. 

 M'1-lnldi-id 1'ii/ii-i'xxiiid MARATTI, De Plantis Xoopliytiw, 1776, p. 27. 

 Sertularia cupressma (.partj GRONOVIUS, Zoophylacium gronovianum, 17si, p. 358. 



