July 3, 1896.] 



SCIENCE. 



11 



Such are the essential features of Pakeo- 

 spondyliis as recorded by Dr. Traquair in 

 ^ The Annals of Scottish Natural History ' 

 (III., p. 94-98, pi. 3, 1894). He main- 

 tained that " there seems no escape from 

 the conclusion that the little creature must 

 be classed as a Marsipobranch " and that, 

 "■ if Palceospondylus is not a Marsipobranch, 

 it is quite impossible to refer it to any other 

 existing group of vertebrates." 



Dr. Dean in a recent note ' on the sup- 

 posed kinship of the Palseospondylus ' (Sci- 

 ence, N. S., 111., p. 214) claims to have dis- 

 covered ' a series of transversely directed 

 rays, arising from the region of the post- 

 occipital plates of Traquair ' which, in his 

 opinion, ' warrant the belief that this lam- 

 prey-like form was possessed of paired fins, 

 a character decidedly adverse to the now 

 widely accepted view of Marsipobranchian 

 affinities.' 



In the case of the little animal in ques- 

 tion, we have to deal with matters of obser- 

 vation first and then of interpretation. The 

 latter, however, largely preponderate for 

 even what is represented as being seen 

 must be the result of interpretation of traces 

 or filling- up of outlines ; of course, then, 

 taxonomic deductions must stand or fall in 

 the ratio of the correctness or failure of the 

 interpretation as well as observation. 



Assuming the correctness of Dr. Tra- 

 quair's description and figures, we certainly 

 have a remarkable combination of charac- 

 ters. On the one hand, if the ' median 

 opening or rim ' is indeed nasal, the ani- 

 mal certainly cannot be referred to the 

 class of Selachians or of Teleostomes. On 

 the other hand, the cranium and the seg- 

 mented vertebral column indicate a more 

 advanced stage of development of the 

 ;»U cY vertebrate line than that from the living 

 Marsipobranchs must have originated. AVe 

 may, therefore, with propriety isolate it as 

 the representative not only of a peculiar 

 family (Paloeospondylidce) , but of an order 



or even subclass (Cyclise) of vertebrates 

 which may provisionally (and only pro- 

 visionally) be retained in the class of 

 Marsipobranchs. 



The group may be defined as Monorrhines 

 with a continuous (?) cranium, a median 

 nasal (?) ring, and a segmented vertebral 

 column. 



The name Cyclise has been constructed 

 on the model of the classical names 

 AcantJiias, Antliias, XipJiias, etc., and is de- 

 rived from yjr/.Xo<s circle, and the termina- 

 tion -m?, i. e., cyclias in the plural number. 

 The word is descriptive and will fit, what- 

 ever interpretation may be put on the ring- 

 like structure. 



The differences between the Hyperoartia 

 and Hyperotreta are very great, and Prof. 

 Lankester did not go much too far when 

 he elevated those groups to class rank. 

 Among the numerous distinctive characters 

 are the great differences in the auditory 

 organs. Perhaps the organs of Palceospon- 

 dylus might be worked out in some specimen 

 and throw light on the subject of affinities. 

 At present even the region of the auditory 

 organs is not exactly known and we are now 

 at a loss to orient the several parts of the 

 cranium. In fact, the question of the 

 relations of Palceospondylus is a very open 

 one. 



Theo. Gill. 



[Just after this note had been sent to 

 Science, and when the review of Dr. Dean's 

 ' Fishes ' was in page form, I had the pleas- 

 ure of receiving from Dr. Dean an extract 

 from the ' Transactions of the New York 

 Academy Sciences, Vol. XY., pp. 101-104, 

 plate Y., ' entitled ' Is Palseospondylus a 

 Cyclostome ? ' Dr. Dean concludes that '' the 

 position of the fossil * -'^ '^ is certainly un- 

 definable," but suggests that " perhaps one 

 might most reasonably place it with the 

 Ostracoderms among the curiously special- 

 ized off"- shoots of the early chordates. "] 



