AIT] NIXIES OF THE GENUS SIPHON!!. 



797 



Chalk sponges and those which live half-immersed and unattached 

 in the Atlantic ooze of the present day. 



1840-41. Romer, P. A. ' Die Versteinerungen des norddentschen 

 Kreidegebirges,' p. 4, tab. ii. figs. 1, 2, 3. 



The genus is assigned, as in all works subsequent to Blainville, 

 to the sponges ; its characters are defined afresh ; and eight species 

 are described from Cretaceous strata, of which three, S. cylindrical 

 (tab. ii. fig. 1), ocellata (ib. fig. 2), oliyostoma (ib. fig. 3), are new, 

 while a fourth, S. Goldfussii, is the Manon pyriforme of Goldfuss, 

 renamed and transferred, I think rightly, to Siphonia. 



S. oliyostoma appears to be a Lithistid of some sort ; but there is 

 nothing to show that it possesses the essential structure of Siphonia ; 

 the two other new species exhibit no characters by which we can 

 determine even their ordinal affinities. 



A reference is made to Choanites as " Seyphia (Choanites) 

 Koenigii" on page 8, where we find its right to generic independ- 

 ence strongly questioned, and its true place indicated as belonging 

 to the Scyphice. 



List op Species. 



8. punctata.* 



8. ficus. 



8. Goldfussii. 

 8. cylindrica. 

 8. ocellata. 

 8. oliyostoma. 

 8. multiformis^ . 



8. cervicornis. 



Upper Chalk Marl 

 Lower ,, ,, 

 Upper „ „ 

 Grey Chalk (Planer) 

 Lower Chalk Marl. 

 Planer. 



Chalk marl (Planer) 

 Lower Chalk. 

 Greensand (glauconie). 

 Lower Chalk Marl. 



Sudmerberg, near Goslar. 

 Usenburg and Coesfeld. 

 Sudmerberg, near Goslar. 

 Steckelnburg near Quedlinburg. 

 Near Coesfeld. 

 Steckelnburg. 



Near Usenburg. 



Near Peine. 



Vouziers, Ardennes. 



Near Lemford and Coesfeld. 



1840-47. Michelin. ' Iconographie Zoophytologique.' 



The additions to our knowledge of the genus made here consist 

 chiefly in descriptions of a number of species, one of which, S. 

 arbuscula, is a very interesting form, since it presents us with a 

 composite $. jpyriformis, characterized by a number of sponge- 

 bodies borne on pedicels branching from the main stem. 



Blainville's mistake in reference to S. typum is repeated, and my 

 opinion in regard to its identity with Alcyonium Jicus, Linn., con- 

 firmed by anticipation. 



In the following list of species those which are printed with an 

 asterisk either certainly do not belong here, or only doubtfully. 



* This is considered identical with 8. incrassata, Golclf. 

 t 8. pistillum is supposed to belong to this species. 



