100 AMERICAN HYDROIDS. 



from both, however, iu its very long internodes, from the former in the degree of exsertion of 

 its hydrotheca?, and from the latter in the form and ornamentation of the gonangia. 



Type slides. Cat. Nos. 19,771, 19,772, U. S. N. M. ; Cat. No. 18,711, Museum State Uni- 

 versity of Iowa; also in the collection of the author. 



SERTULARELLA LEVINSENI, new species. 

 (Plate XXVI, figs. 1-2.) 



Trophosome. Colony very loose and straggling in habit, sometimes attaining a height of 3 

 inches. Stem not fascicled, slender, flexuose, divided into regular internodes each of which bears 

 a hydrotheca or a hydrotheca and branch. Branches irregularly alternate, slender, flexuose, 

 often dividing dichotomously, rarely anastomosing, divided into regular internodes throughout. 

 Hydrotheca? rather small and distant, stout, swollen below, their adcauline wall adnate for from 

 one-half to three fourths its length; margin with three well-marked equal and equidistant teeth; 

 operculum with three flaps. 



Gonosorne. Gonangia borne in rows on stem and all the branches, although they are more 

 apt to be aggregated proximally, small, ovoid, somewhat elongate, with shallow broad annulations 

 particularly on distal portions; neck short but distinct. 



Distribution. Albatross Station 2842, lat. N. 54 15', long. W. 166 03', 72 fathoms. 



This species is allied to S. dichotoma in the general appearance of its trophosome, but differs 

 in having more distant and much larger hydrotheca?, a complete division of stem into regular 

 internodes, and a different gonosome. It is allied to X. frnjiica Hartlaub in the shape of its 

 gonangia, but differs in having smaller hydrotheca? which are much more exserted, and gonangia 

 not nearly so slender. 



I take pleasure in naming this species in honor of Professor G. M. R. Levinsen, whose valu- 

 able papers on the hydroids of northern waters have greatly extended our knowledge. 



Type slides. Cat. No. 19,761, U. S. N. M.; Cat. No. 18,706, Museum State University of 

 Iowa; also in collection of the author. 



SERTULARELLA DENTIFERA Torrey. 



(Plate XXV, figs. 1-2.) 

 Serlularella dentifera TORREY, Hydroida of the Pacific Coast, 1902, p. 61. 



" Trophosome. Stem slender, flexuose, branched. Branches arising within or in place of 

 hydrothecse; similar to stem. Hydrothecse free for three-quarters of their length, tubular, 

 slightly enlarged at base; margin reduplicated, furnished with three moderate teeth forming a 

 triangle with apex nearest stem." 



Gonosome. Not known. 



Disti'tbntiim. San Pedro, California. 



1 have not seen this species, and have copied the original description entire, although there 

 is considerable likelihood that it is identical with S. tr<>j>ic<t Hartlaub. 1 The character given by 

 Torrey, as, " branches arising within or in place of hydrothecse" occurs as a sort of abnormality 

 in numerous species of hydroids that normally branch in the ordinary manner, and it is of doubt- 

 ful value as a means of distinguishing species. 



Type. In the collection of the University of California. 



SERTULARELLA TRICUSPIDATA (Alder). 



(Plate XXV, figs. 3-7.) 



H'l-hiliii-iii ti-iriix/iiilnta ALDER, Ann. and Mag., 2d ser., XVIII, 1856, p. 356. 



N liii/tiriu trirtixjiidatii AI.IIEH, Cat. Zooph. Northumb, 1857, p. 21. 



,s; I'hiliii'in i licoideg MORCH, Rink. Grunland geograph. og statisk beskr., 1857, p. 97. 



Sertularia tricuspidata GREENE, Ann. and Mag., 3d ser., V, 1860, p. 431. 



'See Clarke's description and figures of S. mriabil.it (=/S'. tropicn Hartlaub), Bulletin of the Museum of Com- 

 parative Zoology, XXV, 1894, p. 75, pi. iv, fig. 20, and pi. v, figs. 21 and 22. 



