960 M1?S. O. A, MERRITT HAWKES ox THE [DeC. 11, 



tlie results nvrived at by tl\e less reliable method of maci-o-dis- 

 sectiou. The formalin had made the subcutaneous tissue so hard 

 that thin sections of the skin have at present been impossible, 

 hence the observations made bv means of such sections on the 

 lateral-line canals and the ampulla; of Loi^enzini have not been 

 satisfactoi-v. I expect, however, to obtain better results in time. 



Mr. Cole hoped that the nervous system of so low a species 

 Avould throw some consideiable light upon the nerve-component 

 theoi-y. The external relations of the nerves have proved of great 

 interest, and have given some new and unexpected data, but the 

 nervous system of C7ihi})i)/doseh(chus cannot be considered known 

 until small specimens have been completely sectionised and the 

 animal thus reconstructed. 



Not only the nerves, but every part of C/ihou i/doselachvs has 

 proved of interest, owing to the combination of primitive and 

 specialised characteiistics. These points will, I hope, be eventually 

 submitted to the test of embryological investigation. 



A small bibliography only is appended, as a complete list of 

 papers on nerves can be found in the works of Hei'rick, Cole, 

 and Johnston. 



I wish to heartily thank Professor Bridge for his continual 

 help during the 2:)rogress of this work and for his valuable revisioii 

 of the MS. : Mr. Cole not only for the gift of the specimen, but 

 for suggestions and help on the completed ■\^•ol•k. Thanks are also 

 due to Professor K. J\[itsukuri, of Tokio, who sent the Chlamydo- 

 selackus to INIr. Cole in order that its nerves and sense-organs 

 might be investigated, and to Mr. G. A. Boulenger for references 

 and for loan of books and for permission to examine the specimens 

 in his charge. 



B. The Lateral Lixe System. 



The Lateral Line System comprises canals upon both the head 

 and body, the former being much more complicated than is usual 

 among Elasmobranchs (except Bays and Skates). The parts of 

 the body ovei- which the canals pass wei-e the only relations 

 Carman (10. p. 82) considered in naming the canals, and thus 

 his nomenclature depends upon the appai'ent instead of the real 

 relation of parts. As Carman's names are valueless in compaiutive 

 anatomy, it is no-w necessai-y to rename the canals in accordance 

 Avith Coles method, /. e. with reference to the innei-vation. And 

 as we may take it that a canal innervated by a well-defined nei-ve 

 repi'esents one unit of the system, this method of nomenclature 

 brings analogciiis parts of the system of difi:erent species into line 

 with one another. 



The Supra orhiial canal (Plate LXVIIL fig. 1, B, C, D), which 

 includes the cranial, rostral, and subrosti-al canals of Carman, and 

 is innervated by the superficial ophthalmic bi-mch of the Facialis, 

 passes forward along the top of the head, just above the eye. 

 liike all the closed canals of Cldamydoselachus, it lies immediately 

 under the skin, from Avhich it is not easilv dissected. In front 



