212 D. M. S. Watson — A New Genus of Brachiopods. 



posterior radial — it has grown away from the anal interradius. To 

 this Mr. Wilson's explanation cannot apply. I entirely agree with 

 his emphasis on the pressure exerted by the hind-gut (p. 545) ; but 

 while I admit " push " and^" shove ", I reject "lift" and "pull". 



In discussing the evolution of the Batocrinoidea (p. 671) Mr. Wilson 

 seems to have misunderstood some remarks in the Echinoderm volume 

 of Lankester's "Zoology" (1900, pp. 165, 166), since he writes 

 " Bather, in accepting this theory [Wachsmuth. & Springer's deriva- 

 tion of the tripartite hexagonal base from one of Platycrinid plan] 

 apparently assumes an intermediate step, for in the generic discussion 

 of Abacocrinns he says : ' From the imagined intermediate step (not 

 from Abacocrinns itself) Periechocrinus may have been derived by 

 fusion of 2 BB.'" The quotation is inaccurate, and the interpretation 

 of it wrong. A few lines back I had written : " Between it [the 

 Silurian Abacocr.~\ and [the Ordovician] Compsocrinus we must 

 imagine a form in which the free Kr became biserial, while the free 

 rami forked several times " ; and I continued : " From the imagined 

 intermediate form . . . Periechocrinus may have been derived by 

 fusion of 2 BB." The intermediate form of course resembled 

 Compsocrinus and Abacocrinus in having 4 basals, with the posterior 

 basal truncate and supporting an anal. Also, since Periechocrinus 

 has 3 ba-sals, if these were derived " by fusion of 2 BB ", its ancestor 

 must have had 4 basals. Therefore I neither " accepted " nor 

 " emended " the theory of Wachsmuth & Springer, but my working 

 hypothesis was the one which Mr. Wilson has himself supported with 

 such wealth of argument. 



It is delightful to find a new worker ready not only to ask a heap 

 of inconvenient questions, but to work out the answers to them. 

 I trust that this article has done justice to his suggestive paper. But 

 whether the fault be the author's, or his printer's, or his reviewer's, 

 it is to be feared that the attempt at elucidation has led me yet again 

 into what a good-natured critic once described as my unforgiveable 

 " habit of offering up his own interpretations of what he does not 

 thoroughly understand in the works of other authors". If the 

 account does not tally with Mr. Wilson's intentions, I hope he will 

 forgive me all the same. 



IV. POIKILOSAKOS, A REMARKABLE NeW GeNTTS OF BrACHIOPODS 



from the Upper Coal-measures of Texas. 



By D. M. S. Watson, M.Sc, Lecturer in Vertebrate Palaeontology, University 

 College, University of London. 



(PLATE XIV.) 



INCLUDED in a large series of marine fossils which I collected 

 from the Cisco Beds of Uralian or Upper Coal-measure age at 

 a well-known locality on the west bank of the Salt Creek at Graham, 

 Young Co., Texas, are several fragments of a single very large 

 nautilpid shell. These fragments had lain so long on the sea-floor 

 before they were covered by mud that they have in many cases been 

 much eaten into by sponges and worms, and are covered by adherent 

 organisms, mostly Bryozoa. Attached to them, however, are twenty 



