74 AMERICAN HYDROIDS. 



fathoms (D'Urban); Iceland (Ssemundsson) ; Labrador (Packard); Mediterranean, Gulf of Gas- 

 cony (Pietet and Bedot); Gulf of St. Lawrence (specimens from Sir William Dawson). 



This is one of the oldest and best known of the Sertularidse. The finest specimens that I 

 have seen came from St. Georges Hank. Newfoundland. 



THUIARIA PLUMOSA Clark. 



Tliiiiiii-in jiliniH i.-ai CLARK, Alaskan Hydroids, ISTii. p. 228. 



Thiiiiirin ji/iuniiKii KiRciiExi-Ai-EK Nordisclu- (iattnngen und Arten, 1884. p. 21. 



" TnyilttiKoiiit'. Hydroeaulus simple, erect, very slender at tho. base, increasing in size to the 

 distal end, somewhat twisted jointed transversely, internodes of the proximal portion of very 

 unequal length, some being three times the length of others, those of the upper portion are 

 quite uniform, regularly branched; branches short, arranged alternately, one to each internode. 

 but owing to the twist in the stem take on a spiral form, the uppermost erect, lying close to the 

 stem, the lower ones curve outward, attached to the stem by a very prominent proce.ss, bearing 

 a few branchlets, regularly jointed; branchlets do not extend beyond the ends of 1 (ranches, and 

 lie close to the latter. Hydrothecu? largest at the base, tapering slightly outward, entirely 

 immersed; aperture toward the stem, the outer side produced, rim ornamented with two large 

 teeth placed on the outer side, two tooth-like processes of the perisarc also occur in the base of 

 each hydrotheca, arranged sub-alternately upon the branches and branchlets. Upon the stem 

 there are three to each internode, two placed opposite to each other and one in the axil of the 

 branch. 



"(rontiNinii,'. Gonangia sessile, very long and narrow, tapering gradually to the base, orna- 

 mented with two short horns placed on opposite, sides of the orifice near the distal end; orifice 

 terminal, large; borne in single rows on the upper side of the branches and branchlets. Height 

 of largest specimen, 40 mm. 



"Habitat. Bering Sea, 5 miles southwest of the west cape of Nunivak Island; :-!() fathoms, 

 sand. Icy Cape, Arctic Ocean; 15 fathoms, sand." 



I have not seen this species, and have copied entire the excellent description given by the 

 original describer, Clark. 



Type. Should be in the collection of the U. S. National Museum, but I have been unable to 

 find it there. 



PASYTHEA Lamouroux (in part). 



Trophosome. Hydrothecse biserial, strictly opposite, arranged in groups of pairs, a group 

 to an internode, the upper pair being smaller and differing in shape from the lower; margin 

 bilabiate, with a two-flapped opcrcuhmi. 



(.iiiniiKoini-. Gonangia oval, smooth or with sides marked by broad annular rugosities, with 

 a large aperture and narrow collar. 



This genus was introduced by Lamouroux in 1812 ' to accommodate two unrelated species, 

 one being the well-known J'. ynmlriil, ntntn and the other the so-called /'. f/il/'j)/'//', a bryozoan. 

 It remained for Bale to give an adequate definition 2 which was adopted in 18!i<> by Marktanner- 

 Turneretscher. 3 The group appears to be well defined, with evident relationship to S'-rti/Jar/n 

 in several respects, such as the opposite position of the hydrothecse and the characters of the 

 Irydrothecal margin and operculum. There are but three species known, I believe, one, P. yiiuil- 

 ridentata from both the Atlantic and Pacific, one, P. /i<.,'<><lt>n, from the Australian region, and 

 a third, P. phiMppina^ from the Philippines. 



The American form is typical of the genus as defined above. 



1 Nnuvcail I'.llllrtill .Irs Srirlli'rs ]>ur la Snrirtr phi]<miatii|llr III, Paris, 1812, J>. 183. 



-Australian Ilydrnid /oophytrs, 1SS4, p. 112. 



3 Hydroiden des k. k. naturlustoriyi:h<.-n IlufimiKumns, 1S!IO, p. 234. 



