AFFINITIES OF THE GENTJS SIPEONIA. 799 



enumerates the following species from the " etage Cenomanien " 

 (p. 186):- 



1. Siphonia costata, which includes Hallirhoa costata, Lamx., 

 and H. Tessonis, Mich. 



2. S. acaulis, Mich. 



3. S.ficus, Goldf., which includes Sowerby's 8. pyriformis. From 

 the " etage Senonien" (p. 285) : — 



1. S. lycoperdites, D'Orb., in which are merged S. piriformis 

 and S. incrassata, Goldf. 



2. S. Kbnigii, Choanites Konigii, Mantell, to which he adds, 

 as belonging here, Spongia terebrata, Phil., and Scyphia (Cnemi- 

 dium) pertusum, Reuss. Of course, without a knowledge of the 

 intimate structure of these species, it is impossible to deny the 

 justice of these identifications ; but the figures of Phillips (Geol. 

 Yorks. pi. i. fig. 10), and of Reuss (Bohm. Kreid. pi. xvi. figs. 7 to 

 12), exhibit a very marked difference from the Choanites of Mantell, 

 since they possess only one set of canals, the longitudinal group 

 being absent. 



3. S. tuberosa equivalent to Scyphia tuberosa, Romer (Nordd. Kreid. 

 pi. ii. fig. 9). Eomer figures the minute structure of this sponge ; 

 it is a true Hexactinellid, and has nothing to do with Siphonia. 



4. S. dichotoma is Michelin's Scyphia dichotoma ; and the reference 

 here is doubtful, to say the least, since the minute structure is not 

 known. 



5. S. infundibulum, D'Orb., is Scyphia terebrata, Mich. ; another 

 of those generic identifications which rest on no sufficient basis. 



6 to 9. S. arbuscula, ficoidea, Fittoni, brevicosta, all Michelin's. 



10. S. elongata, Reuss. 



11. S. temata, Reuss. 



12. S. multiformis, Bronn. 



1851. Bronn. ' Lethaea Geognostica,' Th. v. p. 73, t. xxvii. 

 fig. 20. 



Bronn considers that there is no essential difference between 

 Siphonia, Hallirhoa, and Jerea ; at the most they are subgenera. 

 There can be no doubt that as regards the first two he is right ; and 

 with respect to the third the probabilities are in his favour ; the 

 Siphonia of the Folkestone Gault differs in no important particular 

 from the Jerea pyriformis of Lamouroux and Michelin ; but without 

 an opportunity of examining more species of Jerea I do not feel able 

 to pass an opinion upon the whole group. Bronn also describes and 

 figures a new species, Siphonia multiformis (Jerea pyriformis, Defr. 

 Diet. Sci. Nat., Atlas des Polyp, xlix. fig. 2) ; this does not possess 

 the usual central cloaca of Siphonia, but otherwise strongly resembles 

 it. The various other species of the genus, which he quotes and 

 rearranges from, other authors, will be found referred to him in the 

 appended catalogue, pp. 825-833. 



Choanites he maintains as a distinct genus, partly on account 

 of its spiral canal ; and his C. Koenigi is made to include Spongia 

 terebrata, Phill., and Scyphia heteromorpha, Gein. 



