Bibliographical Notices. 409 



it as probable that the posterior radials supported a ventral tube, 

 and this would introduce an asymmetry into the ealys, of which 

 there is no trace whatever in Encriniis. This much they admit on 

 p. 230, where they say : — " In the same degree as paloeontologically 

 the calyx grows more symmetrical, the ventral sac decreases in size, 

 aud probably disappeared entirely in Encrinus, which is closely allied 

 to the Poteriocrinidce." In like manner they describe their speci- 

 mens of Stemmatocrinus Trautscholdi as sliowing " traces of inter- 

 radial plates resting against the inner edges of two radials, of 

 which the places of attachment are plainly visible, and detached 

 plates we]-e placed aside of them." (p, 256). These plates, however, 

 are altogether absent in the Encrinidce, every species of which has 

 the third radial axillary, a character which is very constant among 

 Neocrinoids, and is by no means so in the Poteriociinidas, the second 

 being axillary in Erisocnnus and Stemmatocrinus. Considering these 

 and other points which we are unable at present to discuss, we cannot 

 but feel that M'achsmuth and Springer have not made out their case 

 for the transfer of the Encrinida^ to the Pala3ocrinoidea. The)- express 

 themselves as " willing to admit that Encrinus constitutes a transi- 

 tion form towards the Neocrinoidea, it is even possible that in the 

 adult the interradials become partly or wholly re.sorbed, but it is 

 otherwise so closely connected with the Poteriocrinidse that we must 

 regard it as a Palteocrinoid, or place also the Poteriocrinidce among 

 the Neocrinoidea " (p. 257). When they shall have discovered that 

 the calyx of Encrinus has an azygos side indicating the presence of 

 the ventral tube, which is so characteristic of the Poteriocrinida), we 

 shall be more disposed to agree with them. They say on p. 230, 

 " Comparing Ei-isocrinus with Encrinus, the only noticeable difference 

 in their fossil state is the presence of a single brachial in the former 

 and two in the latter." Put in making this statement they entirely 

 ignore the fact to which they allude on p. 255, viz. that in Eriso- 

 crinus a plate of the ventral tube rests upon the radials, while 

 nothing of the kind occurs in Encrinus ; and yet it is almost exclu- 

 sively upon this point tliat the whole question turns. Their com- 

 parison of Encrinus and Erisocrinus is also incomplete in another 

 resjiect. Not only has Encrinus three radials and Erisocrinus two, 

 but the authors admit, on p. 192, that the two outer radials and the 

 proximal arm-plates of Encrimis are respectively united by syzygy. 

 They ought to know, though they seem to be im aware of it, that 

 this is in accordance with a rule " which holds good in almost all the 

 Neocrinoids "*. But they also expressly state on p. 192 that syzygies 

 are not known to occur in the Poteriocriuid8e, and so furnish another 

 argument against their transfer of Encrinus to the Palasocrinoids. 



The Catillocriuidse and Calctooriuidte arc two extremely puzzling 

 families, the morphological study of which is beset with the very 

 greatest difficulties. We think, however, that Messrs. Wachsmuth 

 and Springer have successfully overcome many of thsic difficui<-ies, and 

 that their analyses of the structure of these curious types will be evcn- 



* Report on the 'Challenger ' Crinoidea, p. -lO. 



