270 Prof. II. J. Clark on the Animal Nature 



subjected. The length of the pectoral fin was also not so great 

 as that figured by Couch. The proportions given in the speci- 

 men killed at Portland are — length of body 30 inches, length 

 of pectoral fin 11 1 inches; while in the specimen examined by 

 mc the length of body was 24 inches, and the pectoral fin 

 8^ inches. This latter length, however, comes quite up to that 

 given by Cuvier for the species. He says the Scomber thynnus 

 has the pectoral fin one-fifth part of its length, while the Orcynus 

 has it one-third the length of the body, and that this difference 

 is the only one between the two fishes. It will be seen, then, that 

 8| inches is nearly the proportion given by Cuvier, being a 

 little more than one-third of 24 inches, the full length of the 

 fish. 



It is fortunate that the pectoral fin was sufficiently perfect 

 to allow of its being accurately measured, and thus enable us 

 to record another instance of this south-of-Europe fish paying 

 a visit to our northern shores. 



It is further worthy of remark that Mr. Couch has reported the 

 capture of the Short-finned Tunny (a fish never before taken on 

 our coasts) on the 16th of August last. It would be interest- 

 ing to know what causes have led these fish so far north on this 

 occasion. 



XXXII. — Proofs of the Animal Nature of the Cilio-flagellate Infu- 

 soria, based upon Investigations of the Structure and Physio- 

 logy of one of the Peridinia (Peridinium cypripedium, n. sp.). 

 By Prof. H. James Clark, A.B., B.S.* 

 [Plate XII.] 

 Whatever tends to elucidate the doubtful nature of any group 

 of beings which stands undecided (as it were on the dividing line) 

 between sentient and non-sentient things has an importance at 

 the present day which would not have been deemed worthy of 

 very grave consideration before the theories of Spontaneous 

 Generation and what is sometimes mistakenly called Darwinism 

 had been revived. The resurgence of these doctrines has given 

 a prominence to the discussion of the character of the lowest, 

 obscure forms of life, simply because, in their extreme simplicity, 

 they hardly seem to rise above a state of inorganic nature, and 

 their vitality is exhibited in such a guise as would readily be 

 mistaken for the operation of exo-endosmotic, inanimate, inor- 

 ganic forces. Hence the readiness, the eagerness, with which 

 the physicists of the Materialistic school clutch at these "toys" 



* Communicated by the Author, having been read before the American 

 Academy of Science and Arts, February 14, 1865, 



