274 



M. K. A. Zlttel on 



the kindness of Dr. Steinmann, is identical with Cylindro- 

 j)hyma. Mr. Linck, hoAvever, points out some peculiarities of 

 these skeletal corpuscles which show that my definition of the 

 Anomocladina is not quite correct. Thus Linck's figures 

 (I. c. Taf. ii. fig. 4) represent isolated skeletal corpuscles, 

 " globularly thickened " at both ends and showing a simple 

 axial canal. The axial canal terminates at both ends before 

 the thickened inflations, and thus, as Mr. Linck justly re- 

 marks, the supposition that several branches meeting together 

 in a node belong to one skeletal corpuscle becomes impos- 

 sible. In Cylindrophyvm^ therefore, as in Astyhspongia, the 

 production of the nodes is to be explained as effected in this 

 way — the thickened or, more properly, branched ends of 

 several skeletal elements meet together and become amalga- 

 mated. The distinction between AstyJospongia and PaJceo- 

 wanon on the one hand and Gylindrophyma ^ Mclonella^ and 

 Mastosia on the other consists chiefly in the fact that in the 

 Silurian genera the straight, rod-like skeletal elements only 

 emit short root-like branches at their extremities, while in the 

 Jurassic forms a stronger furcation of the ends often occurs, 

 and sometimes larger side branches may issue from the main 



Fie:. 3. 



rio-. 4. 







E^^^'-V"^^ 



Fig. 3 a-(l. — Skeleton of Cijlindrophyma miUcporata, Goldf., Upper Jura f, 



Sontlieim. 

 Fig. 4 a-e. — Skeleton of Lecanvlln patcra'fonnis, Zitt., Upper Jura e, 



Sonlheim. Enlarged 25 diameters. 



bar. Mr. Schwager has drawn figs. 3 a-d from an unusually 

 well-preserved specimen of CyJindropliyma from the Upper 

 Jura € of Sontheim ; and these show clearly tlie mode of 

 production of the nodes and the construction of the skeleton, 

 and at the same time prove the typical agreement with Asiylo- 



