440 M. C. Mereschkowsky on neio Hydroida 



then six, and finally seven series at its extremity ; and I have 

 very rarely met with cases in which the end of the branch 

 had fewer than seven series. The form of the hydrothecae is 

 not cylindrical as in most species of the genus, but more or 

 less conical (PI. XVI. fig. 10) and rather elongate ; this last 

 character, however, is not very constant, and occasion- 

 ally we meet with hydrothecas having the ordinary, more 

 or less cylindrical form. The aperture is oval or round, with- 

 out any trace of teeth or even of angles. The hydrothecas of 

 each series are arranged so as to leave small intervals between 

 them. The gonosome has nothing very characteristic about 

 it, and scarcely differs in any way from the normal form ; that 

 is to say, it is oval, truncate above, and narrowed below. 



Length of the entire colony 75 millims., breadth 15 ; width 

 of the branches 0*7 ; length of hydro thecffi 0*45, maximum 

 breadth 0*25 ; length of gonotheca?. 0'7, their width 0*5. 



The Academy of Sciences of St. Petersburg only possesses 

 a single specimen of this species, the ticket belonging to which 

 has been lost, so tliat the only locality I am able to give is 

 the Northern Pacific Ocean ; but it is very probable that the 

 species comes from the sea of Ochotsk or from Kamtschatka. 

 Selaginopsis tlmja is distinguished by its mode of ramification 

 (six branches), by the form of the colony, and by the form of 

 the hydrothecae and tlieir arrangement in six or seven series. 



5. Selaginopsis ochotensis, sp. n. (PI. XVI. figs. 11, 12.) 



Trophosome. Hydrocaulus straight, angular, bearing branches 

 on all sides, which are attached by means of a cylindrical 

 tube springing from the stem. Each branch divides at some 

 distance from the point of attachment into six long and broad 

 branchlets. HydrothecEe arranged in several regular series, 

 viost frequently in eight or nine, and at the same time spirally; 

 they are not entirely immersed in the substance of the axial 

 tube, but their ends project. Aperture compressed, fur- 

 nished with two large teeth. 



Gonosome. Gonangia arranged along the whole length of the 

 branches, pyriform, with a straight, not bent neck, and with 

 the surface smooth. 



Locality. Sea of Ochotsk {M. DJuktshandran, 1844). 



Tliis species, of which the Museum of the Academy pos- 

 sesses two specimens, is very characteristic, and quite distinct 

 from all the others that I have just described. The hydro- 

 caulus is broad and angular, and bears branches on all sides 

 in such a fashion as to form in the whole the habit of Thujaria 

 thuja, but much more robust than the latter in consequence of 

 the greater breadth of the branches. At the apex of the 



