TUBULARIA TENELLA. 415 



Tliongli Aj^assiz raises tlie present species to tlie rank of a separate genus nnder tlie name 

 of Thnintocnidia, lie gives no precise diagnosis of it either generic or specific, and I liave been 

 obliged to content myself witli simply quoting his remarks as above. The beautiful figures, 

 however, which accompany these remarks will greatly aid in identification. 



The new genus Thamnocnidia, which Agassiz forms for the present species, appears to be 

 based on the form of the tentacula-like processes of the gonophore, and the apparent absence of 

 those parietal canals which in the gono{)hores of Tubidaria indivisa represent the gastrovascular 

 canals of the more developed medusa — characters which I do not regard as sufficient to justify a 

 generic separation. 



To liis genus Thamnocnidia Agassiz also refers the Tubidaria larynx of the European shores 

 and the Tubidaria {Thamnocnidia) fenella, Agassiz, a new species of tlie Atlantic shores of North 

 America. 



* 



13. TUBULAUIA TENELLA, Agassiz. 



Thamnocnidia texella, — Agassiz, Cont. Nat. Hist. U. S., vol. iv, p. 275, pi. xxii, figs. 



21 — 30. Alex. Agassiz, Illus. Catal. N. A. Acal., 

 p. 195. 



" Although this species agrees so closely in nearly all its details with Thamnocnidia {Ttihu- 

 laria) sjiecfabilis, it has a very different habitat ; it is never found with its congener in brackish 

 water, but always in the open ocean, among rocky pools. It is a very delicate, graceful animal, 

 and much the smallest of our Tubularians, having about half the size of Thamnocnidia spcctabiJis 

 or Pari/pha crocea. It branches very irregularly, loosely, and openly, with a stem of uniform 

 thickness throughout, about as large as a common sewing needle, or, to be more exact, one 

 fiftieth of an inch in diameter. The medusoids have been observed in January, -July, August, 

 and December." — Agassiz. 



Habitat . — Kocky pools in the open ocean. 

 Locality. — Massachusetts Bay, Agassiz. 



The above is the only account Agassiz has given us of this species, which he refers to his 

 genus Thrnnnocnidia. His remarks do not contain sufficient detail to admit of the construction 

 of a technical diagnosis, and I have, therefore, as in the preceding species, been obliged to content 

 myself by simply quoting his words, and referring to the beautiful figures by which the external 

 characters of the species and certain structural details are represented. 



