96 AMERICAN HYDEOIDS. 



in shape, but thoir contours are gracefully curved, the basal portion being broader, gradually 

 narrowing in central parts and again broadening toward the distinctly everted margin. The 

 margin itself is smooth. • The diaphragm is low and the basal chamber small. The hydranth 

 has the characteristic structure of this family, the real mouth being depressed considerably 

 below the level of the general oral surface. This, which one would naturally consider as the 

 proboscis, unless sections were examined, is a dome-shaped or conical structure with an apical 

 aperture and a Hning of ectoderm. In section it reveals the two layers of ectoderm with a 

 stutzlamella between them; the tentacles are numerous. 



Gonosome. — The gonangia gi-ow in clumps or clusters, resembling those of Lafoea, but are 

 not so closely aggregated as is usual in that genus. They are usually less than half as high 

 as the hydrothecae and are cylindrical, with very distinct annulations 5 or 6 in number. The 

 distal end is truncated. The whole gonangium greatly resembles the common form found in 

 campanularians, e. g., Clytia joJmstoni. The gonangia contain developing medusae, the special 

 characters of wliich can not be made out. 



Distribution. — Type-locality, Orca, Prince William Sound, Alaska. Also found by the 

 Alhatross at the following stations: Station 4778, lat. 52° 12' N.; long. 179° 52' E., 43 fathoms 

 (Bering Sea); station 4803, lat. 46° 42' N.; long. 151° 45' E., 229 fathoms (ofi' Kamchatka); 

 station 4804, lat. 46° 42' N.; long. 151° 47' E., 229 fathoms (off Kamchatka); station 4809, lat. 

 41° 18' N.; long. 140° 8' 40" E., 207 fathoms (Sea of Japan). Nearly every writer who has 

 mentioned this species since it was originally described has regarded it as a synonym of Bonr- 

 neviella grandis. Upon direct comparison of the two forms, however, they are seen to be very 

 distinct and undoubtedly good species. In the trophosome there is a striking difference in 

 the character of the stem, B. grandis having a true fascicled stem made up of straight, closely 

 adherent tubes, while the stem in B. regia is an aggregation of distinct rootstocks which are 

 usually plainly separate. The hydrothecse differ not only in size, those of B. grandis being 

 much larger and more robust than in B. regia; but they differ still more remarkably in text- 

 ure, the hydrothecse of B. grandis being coarse and somewhat opaque as is usually the case in 

 Lafoea, while those of B. regia are so exquisitely transparent and dehcate that, in spite of their 

 large size, they are hard to make out with a hand lens when in a small vial. The gonosome differs 

 even more than the trophosome, that of B. grandis consisting of terete and longitudinally 

 ribbed gonangia, while those of B. regia are cyhndrical and transversely corrugated. 



BONN^VIELLA SUPERBA, new species. 



Plate 27, figs. 1-3. 



TrofTiosome. — Colony consisting of a tangled mass of partly adherent tubes which form an 

 axis or stem from which single pedicels arise. This pseudo-stem is interwoven with a mass of 

 other hydroids, mostly sertularians. Pedicels strong, stiff, attaining a length of 2.5 cm. and a 

 diameter of over 1 mm. They are perfectly smooth, for the most part, but are constricted 

 near their origin and just below the hydrotheca. Hydrothecse enormous, in one case attaining 

 a length of 1.7 cm.; probably the longest hydrotheca known. The diameter near the margin is 

 6 mm. The general shape is deep campanulate rather than tubular, diminishing gradually below 

 until it passes into the pedicel and flaring at the margin above. Margin perfectly smooth. 

 There is no real diaphragm, although there appears to be one, as the bottom of the hydranth 

 is free from the hydrothecal floor. There is no chitinous shelf, however. 



The hydranths are very large, with a single circlet of smooth tentacles. There is no pro- 

 boscis, the surface, which would, without histological investigation be taken for the oral disk, 

 being almost perfectly flat. A longitudinal section of a hydranth shows that this apparent 

 oral surface is in reality the "veloid" of Broch and that it covers a distinct preoral chamber 

 of considerably greater size than that of B. grandis, wliich is, as in that species, lined with ecto- 

 derm. Below this and perhaps partly surrounding its conical lower part is the gastric cavity, 

 lined with convoluted endoderm 



