FORMATIONS AND FOSSILS OF SOUTH MANCHURIA 39 



smaller stems arise. The small stems are also subcylindrical, vary- 

 ing in diameter from 1.5 mm to 4.5 mm and in turn branching di- 

 chotomously many times at intervals of approximately 10 mm. The 

 surface of the stems is apparently somewhat roughened, for when 

 the preservation is good the surface is seen to be covered by very 

 minute pores, which Ulrich and Everett regard as the interstices 

 of the reticulate skeleton. Among these minute pores, a small num- 

 ber of comparatively larger ones may be detected, which I think are 

 the openings of the canal system. 



Sections show that the interior of the branches is mainly occupied 

 by rather thick walls, which are now crystalline calcite and which 

 preserve only very faint traces of the interwoven fiber skeleton. 

 From Plate 10, Figure 3, it is clear that this species belongs to 

 Cmnarocladia, having dichotomously branching stems, a minutely 

 pored surface, and a faintly preserved interwoven fiber skeleton with 

 a confluent canal system. 



Comparison. — The Manchurian species is readily distinguished 

 from the described American species by its general outline and the 

 more complicated branchmg system of the stems, and from the other 

 Manchurian forms in such fashion as described in each case. 



Formation and locality. — ^Middle Ordovician, Ssuyen formation: 

 In the uppermost horizon of the black-banded limestone near the 

 Pen-hsi-hu colliery, Liao-tung, Manchuria. 



Eolotype.—V.^.'^.M. No. 83622. 



CAMAROCLADIA FUCOIDES, new species 



Plate 10, Figubes 1, 2 



Description. — Sponge ramose, branching dichotomously at inter- 

 vals of 7 mm, on an average. Branches subcylindrical with diam- 

 eters varying from 1.3 and 2.5 mm. Parts of the surface of the 

 stems are smooth, while others are somewhat roughened and irregu- 

 larly porous. Among these minute pores larger ones may be de- 

 tected. 



Sections show that the interior of the branches is occupied by 

 more or less confluent subcylindrical cavities and the separating 

 partitions, which are composed of crystalline calcite, preserve only 

 faint traces of the fiber skeleton. These cavities appear to be ar- 

 ranged rather regularly. 



Formation and locality. — Same as preceding. 



Holotype.—V.^.'^.M. No. 83623. 



