110 AMERICAN HYDROIDS. 



Tfujiliiixiiiiii'. Colony attaining a height of 3 or 4 inches. Stem not fascicled, proximal part 

 smooth and without regular nodes, remainder divided into regular internodes each of which bears 

 a pair of hydrothecse and sometimes a branch. Branches irregularly alternate, the proximal 

 internode bearing a pair of hydrothecse as do all the others; branches often terminating in a long 

 hooked, tendril-like process and often dividing into branchlets. Hydrotheca 3 opposite, tubular, 

 rather short and stout, those of a pair rather widely separated, adnate to branch for about 

 three-fourths their height, the distal one-fourth being abruptly divergent and ending in a large 

 broadly sinuous margin, the aperture reaching nearly or quite to the branch. Operculum a 

 single large adcauline flap. 



Gonnxiniii . Gonangia borne in rows on front of branches. Female gonangia oblong-ovate 

 in general outline, the summit crowned by four long pointed lobes or flaps of equal size, 

 converging above. The appearance of an internal marsupial chamber is present in mature speci- 

 mens. Male gonangia much smaller, summit quadrangular, with each angle produced into a 

 tubular process and the center occupied by a small tubular neck terminating in a minute aperture. 



Distribution. New England coast (Verrill); Grand Manan (Stimpson); mouth of St. 

 Lawrence (Whiteaves); British coasts (Johnston); west coast of Greenland (Levinsen); Tromsoe, 

 Norway (Sars); Iceland (Ssemundsson); U. S. Fish Commission Station 770, Narragansett Baj 7 , 

 Si fathoms. 



This species seems to be confined to shallow water. 



DIPHASIA TROPICA, new species. 

 (Plate XXX, fig. 1.) 



Tropkosome. Colony unbranched, arising from a creeping root-stalk and attaining a height 

 of one-fourth inch. Stem slender, not fascicled, divided into regular internodes, each of which 

 bears a pair of strictly opposite hydrothecae. Hydrothecse tubular, five-sided, contingent in 

 front for nearly half their length, scarcely touching each other on the posterior side of stem. 

 Three of the sides of each hydrotheca are seen from the front and two from behind. Distal half 

 free and curving regularly outward and a little upward. Margin circular, aperture closed by an 

 operculum which is adcauline in position. The hydrothecse are ornamented throughout by 

 pronounced compressed external ridges running entirely around the walls, closely set and parallel 

 to each other, forming a conspicuous and unique ornamentation. Pairs of hydrotheca? are 

 separated by about their own height. 



ffonosome. Not known. 



Distribution. Shallow water between Eleuthera and Little Cat Island. Collected by the 

 Bahama expedition from the State University of Iowa. 



The beautiful and regular annulation and the five sides to the hydrotheca' arc features that 

 render this species peculiarly striking and distinct. 



Tyj" */"/< .*. Cat. No. 1980-1, U.S.N.M.; Cat. No. 18729, Museum State University of Iowa; 

 also in collection of the author. 



DIPHASIA DIGITALIS (Busk). 

 (Plate XXX, iigs. 2-7.) 



ilii/iln/ix BI-SK, Voyage of Unltli-siinh.; I, 1852, pp. 387, 3! 13. 



inii/Hlii'cn ALLMAN, Mem. Mus. Comp. Zool., V, No. 2, 1877, p. 26. 

 iliijilnlix BALE, Australian Hydroid Zoophytes, 1884, p. 101. 

 Desmoecyphus acanthocarpus ALLMAN, Challenger Report, Hydroida, Pt. 2, 1888, p. 73. 



Tropkosome. Stem not fascicled, attaining a height of about 4 inches, divided into regular 

 but obscure internodes, each of which bears a pair of opposite hydrotheca} and occasionally a 

 branch. Branches irregularly alternate, arising from short processes which spring from the 

 postero-lateral surface of the stem, rigid, divided into regular internodes, each of which bears a 

 pair of hydrotheca' on its anterior face. Hydrotheca? borne on front of the stem in pairs the 

 individuals of which are contingent on their adcauline sides for almost their entire length, long, 



