400 TUBULARIA INDIVISA. 



ever, that there is here no important difference. I have carefully compared the sporosacs of 

 Tuhularia larynx (= T. coronafa, Abildg.), a species which Agassiz refers to his genus Thamno- 

 cnidia with that of Tubularia mesembryanthemum, mihi, a Mediterranean species which would 

 certainly be referred by Agassiz to his genus Parypha, and the only difference of importance I 

 can find between them is the conical form of the apieal processes in T. larynx (see Plate XXIII, 

 figs. 21, 22, 24) and their laterally compressed crest-shaped form in the female sporosacs of 

 T. mesemhryanthenuuH (see woodcut, figs. 83, 84, page 419). In both cases these processes 

 contain a cavity, but the cavity is more conspicuous in the crest-shaped processes regarded by 

 Agassiz as characteristic of his genus Parypha than in the conical processes which characterise 

 his genus Thamnocnidia. Of the three new genera, then, which Agassiz has constituted for the 

 reception of certain forms included by other .systematists in the genus Tuhularia, I can only 

 admit the validity of one, and it is therefore to this one alone {Ectopleicra) that I have assigned a 

 generic rank in the present monograph. 



I do not, however, wish to depreciate too much the value of the characters assumed by 

 Agassiz as distinctive of the others; and 1 believe that these characters may be conveniently made 

 the grounds of a subordinate grouping of the genus Tubularia. I shall, therefore, employ 

 Agassiz's names for the designation of the subordinate groups or sub-genera thus constituted. 



Among the characters which must be regarded as of value in determining the limits of the 

 species included under the genus Tuhularia, is one which has been hitherto unrecognised. It is 

 afforded by a remarkable condition of the ccenosarc inmiediately below the summit of the stem, 

 and shows itself in the presence of a collar-like expansion of this part, convex on its upper 

 surface, which is always marked with rather deep, radiating flutings, and slightly concave on the 

 lower. I believe that it is only the ectoderm which participates in the formation of this collar. 

 It is entirely absent in Tuhularia indivisa, but in Tuhularia lanjinr, and all other species of this 

 genus which I have had an opportunity of examining, it is present. 



So far as we can determine from the data before us, species 1 — 4 in the following 

 enumeration would be referred by Agassiz to Tuhidaria ; 5 — 15 to Thamnocnidia; and 15 — 17 

 to Farypha. 



At' Sub-genus, Tubularia proper, Agassiz. 

 Sporosacs with conspicuous gastro-vascular canals. 



1. TuBULAEIA INDIVISA, LinncBus. 

 PLATE XX. 



Adianthi AUKEi MINIMI FACIE PLANTA MARINA, — RttU, Sjn. 31, 4. Jussieu, in Mem. Acad. 



Eoy. des Sci., 1742, p. 296, tab. x. 

 Tubular coralline, like oaten pipe, — Ellis, in Phil. Tiaus. for 1754, p. 504, tab. xvii, 



fig. D. 

 Corallina tubularia calamos avenaceos referens, — Ellis, Coral!., p. 31, tab. xvi, fig. C, 



