Gr. R. VINE ON STOMATOPOR^S AND ASCODICTrA. 



613 



41. Silurian TJniserial Stomatopor^e and Ascodictta. By George 

 Robert Vine, Esq. (Communicated by Professor P. Martin 

 Duncan, F.R.S., E.G.S.) (Head June 22, 1881.) 



The genus Alecto was founded by Lamouroux in 1821 for a group 

 of adherent Polyzoa. In 1814 Leach had used the word Alecto for 

 a genus of Echinoderms ; and Mr. Hindis says that it is still employed 

 in connexion with the Crinoidea. On this account its further use 

 for species of Polyzoa is objectionable. In 1825 Prof. Bronn used 

 the word Stomatopora, and in 1826 Groldfuss used Aulopora,, as 

 names for individuals of the same genus as that founded by Lamou- 

 roux. For uniserial species d'Orbigny employed Prof. Bronn's 

 name ; but Blainville, Johnston, Milne-Edwards, Busk, and Defrance 

 used the original word " Alecto " for species described by them in 

 their various writings. 



The generic characters of Stomatopora have been given by various 

 authors ; and additions have been made from time to time. The 

 rather full description given by Goldfuss* of Aulopora dichotoma, 

 together with figures of the species, renders identification compara- 

 tively easy. But somehow there has been a confusion in later 

 identifications, and the Aidopora intermedia f type of Miinster has 

 been mixed up with Goldfuss's type. Both of these are present in 

 the Jurassic formation ; and it is, I will admit, rather a difficult 

 matter to say where the one ends and the other begins. If, how- 

 ever, authors would distinguish between the two types, we should 

 be able to get at the true range of the species, because each has an 

 individual facies of its own. Hall, in describing the species found 

 in the Trenton Limestone of America? (Trenton Falls, Oneida 

 county), makes this distinction: — In Alecto inflata we have the 

 tubes short and individually separate ; whilst in Aidopora arachno- 

 idea the tubes are not distinct or separated from the general con- 

 sistence of the branch. Jules Haime, in his descriptions of the 

 fossil Bryozoa of the Jurassic rocks, places the whole of his species 

 under one genus ; and I prefer this method rather than object to it. 

 Thus, Stomatopora antiqua from the Inferior Lias of Yaliere, S. 

 Terquemi from the Inferior Oolite, and S. Boucliardi from the Ox- 

 ford Clay are of the Aulopora intermedia type ; and this holds good 

 with species found in our own country. Stomatopora dichotoma, 

 S. dichotomoides, D'Orb., and S. Waltoni are of the same type as 

 that given by Goldfuss as Aidopora dichotoma. In S. Desondoni, 

 Haime, from the Inferior Oolite of Longwy, we have a passage- 

 form between Aulopora intermedia and the genus Proboscina, and 

 then species of Proboscina passing by gradations, with a tendency 

 on the one hand to the Idmonece, and on the other to the larger 



* Petrefacta Germanise, p. 218, pi. 65. f. 2. 



t Ibid p. 218, pi. 65. f. 1. 



\ Palaeontology of New York. vol. i. p. 77. 



