202 Mr. A. Adams on the Japanese Species of Siphonalia, 



order, but points much more precisely to the irritable and contrac- 

 tile tissue of the lowest animals, which possess neither muscles 

 nor nerves. 



9. As it is, on the one hand, most improbable that these con- 

 ditions should obtain in the tissue of the filaments of Centaurea 

 as a solitary instance, so, on the other, it is much more credible 

 that similar properties (motory phenomena consequent on irrita- 

 tion) prevail throughout the vegetable kingdom. That this is 

 so, is exemplified in all those movements which have a recog- 

 nized object, as those of the young parts of all plants towards 

 the light, and in the curved motions of such parts induced by 

 mechanical and electrical contact; and the conclusion is inevitable, 

 that irritability and contractility, or, in other words, the faculty 

 of undergoing changes in form or outline in response to external 

 excitation, are not restricted to the animal kingdom, but, like 

 assimilation, respiration, the distribution of nutritive juices, de- 

 velopment, &c., are the vital endowments of the cell simply 

 as such, and are manifested in plant-tissue only exceptionally 

 with less distinct energy by reason of a simpler organization and 

 weaker vital power. 



10. Teleologically considered, the irritability of filaments is 

 subservient to the production of movements in the Cynarese and 

 the florets of probably all the other Compositse, in connexion 

 with dichogamic fertilization, as the frequency of bastard forms 

 in Cirsium and Hieracium indicates. In this process insects 

 constitute the principal agents, causing by their contact the 

 contraction of the stamens and the consequent extrusion of 

 pollen from the anthers, and then carrying the pollen so dis- 

 charged to other florets, the stigmas of which are (unlike the 

 organ of the floret, with its highly irritable stamens, which has 

 furnished the fertilizing powder) in a condition to receive it. 



XXII. — On the Japanese Species of Siphonalia, a proposed new 

 Genus of Gasteropodous Mollusca. By Arthur Adams, 

 r.L.S. &c. 



Genus Siphonalia, A. Adams. 



Testa ovato-fusiformis, plerumque variegata, non epidermide in- 

 duta ; anfractu ultimo ventricoso, plerumque nodoso-plicato. Aper- 

 tura antice in canalem curtum recurvatum desinens. 



Most of the typical species comprising this group have been 

 described by Lovell Reeve in his Monograph of Buccinum. 

 They are, B. cassidariceforme, Rve., B. lineatum, Kien., B. signum, 

 Rve., B. modificatum, Rve., B. spadiceum, Rve., B.fusoides, Rve., 

 B. hinnulm. Ad. & Rve. Their operculum, however, is fusoid, 



