ON rossiL roLYzoA. 165 



to Fiilodidya lanceolata, Lousd., and P. Uimeolata, Goldfuss, there seems 

 to be a little confusion iu our varied identifications of species. lu the 

 Catalogue of Cambrian and Silurian Fossils,' all the P. lanceolata found 

 in the Upper Llandovery to the Upper Ludlow series, with the exception of 

 one species found in the 'Weulock Limestone, are ascribed to Lonsdale. The 

 Wenlock species is identified as that of P. lanceolata, Goldfuss. This con- 

 fusion is to be regretted, and in justifying the course taken by Mr. E. T. 

 Newton in the Catalogue, I would suggest that the Wenlock shale species 

 receive a new name — P. Lonsclalia. There are many characters in this 

 species distinct from the species described by Goldfuss as Flustra lanceo- 

 lata. . There is also a pressing necessity that the types of Ptilodictya 

 should become fixed, either as a genus or as a family. 



Ptilodictya scalpellum is a type somewhat diiferent from that of other 

 species, and under a family name — PTiLODiCTiDiE — I should reconsider 

 my own reference to this genus of the carboniferous Sidcoretepora.- 



Professor Nicholson^ has added much to our knowledge of this group, 

 by the publication in this country of his papers on American forms. He 

 has also founded two new genera to take in what he considers to be allied 

 types. The Upper Sil. species, which are new, are: 1. P.falcifonnis, Nich.f " 

 allied to Uscharopora recta, Hall. His species, however, differs from 

 Mustra {Ptilodictya) lanceolata, Goldf. P. gladiola &ndi P. sulcata, BiWingfi, 

 2. P. emacerata, Nich., a beautifully delicate species, with ' elliptical cells, 

 their long axes corresponding with that of the branches, six or seven in 

 the space of one line measured longitudinally.' ' This Nicholson con- 

 siders to closely resemble P. fracjilis, Billings, and it is possible that it 

 may be only a variety of Billings' species.' * 3. P. flagellimi, Nich. : 

 This also resembles P. gladiola, Billings, and it also very closely re- 

 sembles the P. Lonsdalia of our own Wenlock shale, excepting that 

 the ' attenuated base ' of our own species is rarely ' flexuous,' but more 

 often truncated and round. 4. P. fenestelliformis,^ Nich. : All these 

 species are typical, having the non-poriferous margins and the central 

 laminar axis. One species — Ptilodictya ? arctiopora, Nich. — has affinities 

 with P. raripora. Hall ; but Nicholson doubts the possibility of keeping 

 these two species with the genvis. The cells closely rese_mble_ some of 

 the characters of our own Silurian species, but as there is evidently a 

 departure from the original types, it maybe as well to study these passage 

 forms, if such they be, more carefully than they have yet been done. 5. 

 P. cosciniformis,^ Nich. : Hamilton formation, Bosanquet, Ontario. 



For species allied to Ptilodictya, Nicholson has founded two new genera, 

 and adopted one from Hall. 



1874. Tceniopora, Nicholson, Geological Mag. 1874. 

 „ Clathropora, Hall, „ „ „ 



1875. Heterodictya, Nicholson ,, ,, 1875. 



In Tceniopora we have a zoarium that is a flattened, linear, calcareous 

 expansion, with cells on both sides, the branches of which are dichotomous. 

 There is a median ridge on each face of the zoarium having a longitudinal 

 direction, on the lateral halves of vvhich the cells are developed. These 

 are longitudinally placed in rows of from three to five. The margins are 



' Ifus. of Practical Geology, 1878. 



" Carhoniferous Polyzoa, B. A, Rep. 1880, 2nd page of Report. 

 » An. ]Lag. Nat. Hist. March, 1875. " Ibid. p. 179. 



* MeJwlson, Geo. Mag. Jan. 1875. 



