246 Royal Society: — 



they do not absolutely prove, his case — namely, that the surface and 

 bottom Glohigerinai are perfectly distinct forms, and that the latter 

 are never to be found off the bottom. 



It is impossible for ua hero to follow the author through the long 

 series of statements put forward by him in support of his view ; 

 and we must conclude this brief notice by simply stating that his 

 little pamphlet fiu'nishes a most useful resume of the present state 

 of knowledge on this interesting subject, even apart from the argu- 

 ment which constitutes the foundation of the whole. The book is 

 illustrated with a plate copied from the author's ' North- Atlantic 

 8ea-bed.' 



PROCEEDINGS OF LEARNED SOCIETIES. 



EOYAL SOCIETY. 



December 16, 1875. — Dr. J. Dalton Hooker, C.B., President, in 



the Chair. 



" Preliminary Observations on the Locomotor System o£ Medusae." 

 By a. J. Romanes, M.A., F.L.S. 



I. Movements of the Mednsce. 



The movements of some of the Medusae (e. g. JSarsia) appear to 

 be as voluntary as are those of insects. Some of the discophorous 

 species of naked-eyed Medusae*, when threatened with injury, 

 manifest peculiar movements, which are quite distinct from the 

 ordinary locomotor contractions. These movements consist in a 

 very strong and protracted systole, followed by a slow and gradual 

 diastole. This spasm-like series of movements is never performed 

 by any Medusa except when the animal is being injured or 

 threatened with injury. 



II. Fundamental Observations. 



§ 1. In the case of all the naked-eyed Medusae which I have 

 this year been able to procure (viz. thirteen species belonging to 

 six of the most divergent genera) I find it to be true that excision 

 of the extreme periphery of a nectocalyx is followed by imme- 

 diate, total, and permanent paralysis of the entire organ. The 

 severed margin, on the other hand, continues its rhythmical con- 

 tractions as vigorously as when it was still in situ, and this for many 

 hours after the operation. Among hundreds of observations I 

 have only met with one exception to the otherwise uniform result 

 of this operation. The exception occurred in an indiAidual be- 

 longing to the species iHaurophora laciniata. 



* I adhere to Forbes's classification only because I have not happened to 

 meet with any individuals of the family Lucernariadse. 



