326 M. K. A. Zittel on Fossil Lithistidce. 



with the habit of C. stellatum, rtmulosum, &c. ; but unfortu- 

 nately the French authors (D'Orbigny, Fromentel, Pomel) 

 preferred to regard C. lamellosum as tlie type of the genus. 

 The name has since been appHed to the most various calca- 

 reous and siliceous sponges ; and its suppression seems to be 

 the only certain way to avoid confusion. 



In Quenstedt's latest work (Petref. vol. v.) there are, on 

 plates 126, 127, and 128, numerous very accurate figures of 

 Upper-Jurassic forms, generally much rubbed, which admi- 

 rably illustrate the external appearance and the canal-system. 

 Goldfuss's species, especially G. stellatum^ are rather arbi- 

 trarily treated by Quenstedt. 



Geological distribution. In the Jurassic formation. 



Species : — 



1. Cnemidium stellatum^ Goldf. iv. 2t (non xxx. 3). 

 CnemiiUmn f/ranulosum, Miinst. Goldf. xxxv. 7. 

 Cnemisponyia Guldfussi, Quenst. Petr. cxxvi. 73, 74, cxxvii. 1-16. 



2. Cnemidium striato-punctatum, Goldf. vi. 3. 

 Cnemispongia Goldfussi p. p., Quenst. Petr. cxxvii. 19-22. 



3. Cnemidium corallinum, Quenst. Jura, p. 84. 1 ; Petr. 

 cxxvii. 16-18. 



4. Cnemidium rimulosum^ Goldf. vi. 4; Quenst. Petr. 

 cxxviii. 1-5. 



Tragos yranulosum, Quenst. Petr. cxxviii. 4, 5. 



5. Cnemidium pluristellatum^ Zitt. 



Cnemidium stellatum, Quenst. (non Goldf.) Jura, p. 676; Petr. 



cxxviii. 6, 7. 

 ?Cnemid{u7n stellatum, Goldf. xxx. 3 (non iv. 2). 



*6. Ackilleum tuberosum, Miinst., Goldf. xxxiv. 4. 

 *7. Achilleum cancellatum, Miinst., Goldf. xxxiv. 5. 

 8. Cnemidiastrum Hoheneggeri^ Zitt. Lower White Jura, 

 Wodna, near Cracow. 



COEALLIDIUM, Zitt. 

 Cnsmidium p. p., Quenst. 



Sponge top-shaped, skittle-shaped, or cylindrical ; vertex 

 with a narrow stomachal cavity, from which radiate numerous 

 extremely fine furrows, which traverse the sponge-body as 

 vertical fissures. Sides completely coated with a dense, some- 

 what wrinkled envelope. 



A single species in the Upper Jura of Kelheim. 



1. Cnemidium diceratinum, Quensi Handb. 1852, Ixi. 20; 

 Petr. cxxviii. 10-12. 



t These references tlirougliout are to plates and figures, except where 

 otherwise expressed. 



