418 TUBULARIA MESEMBRYANTHEMUM. 



verticil, the distal circlet composed of at least two series, and containing eighteen or 

 more tentacles. 



GONOSOME. — GoNOPHORES -with "eight rows of thread-cells, which run up the 

 outer surface like meridian lines," and with from four to eight laterally compressed 

 tentaculiform processes which surround a very distinct orifice at the distal end.^ 



Colour. — Ilydraiiths rose colour, cceiiosarc varying from yellow through reddish-yellow into 

 rose colour. 



Development of Gonosome. — From March to September. 

 Habitat. — On rocks exposed to the ocean, near low-water mark. 

 Hathymetrical distribution — Laminarian zone. 

 Localiti/. — Sulivan's Island, South Carolina, M'Crady. 



Though no figure of Tiibnlaria cnstata is given, and though some points of value in a specific 

 diagnosis — such as the simple or branched condition of the hydrocaulus, the erect or pendulous 

 condition of the gonophore clusters, and the presence or absence of gastro-vascular canals — have 

 been left unnoticed in M'Crady's description, there is yet sufficient detail to show that the species 

 is a well-marked one. 



The peculiar bands of thread-cells, which extend in meridional lines along the outer surface 

 of the gonophore, present a striking character, and call to mind what would seem to be a similar 

 feature in the gonophore of Van Beneden's Tabularia Duiiioriieri, for which Agassiz constitutes, 

 as I believe wisely, a new genus, under the name of Ectojjleura. 



The orifice in the summit of the gonophore of Tabularia cristata is occasionally so large as to 

 allow of the extremity of the manubrium being protruded through it, a fact also noticed by Agassiz 

 in his Tabularia (Paryphd) crocea. 



The Tabularia cristata is also one of those species for which Agassiz constitutes his 

 genus Paryplta. 



*^* 17. TUBULAUIA MESEMBRYANTHEMUM, Allinan. 



TROPHOSOME. — Hydrocaulus consisting of a cluster of simple slender stems, 

 destitute of annulation, springing from a plexus of filiform tubes, and attaining a 

 height of about four inches ; ccenosarc forming a collar below the hydranth ; stem not 

 longitudinally striated. Hydraktus with from twenty to twenty-four tentacles in the 



^ It is possible that these processes are coufiued to one sex, though no statement to that effect is 

 made in M'Crady's description of the species. 



