30 Mr. J. Morris on the genus Pollicipes. 



our meadows another eminently social plant, Polygonum persi- 

 caria, often struggles among them. Erica vulgaris covers large 

 tracts in the temperate regions of Europe; Ericacece generally 

 consists of social plants. Filices, Musci, Leguminosce, CompositcB, 

 and many other natural groups, contain numerous instances. 

 Within the tropics some species of Cactus, Aloe, Bromelia and 

 Agave become great nuisances from their social habits. Many 

 display this character simply because there is no check to their 

 mode of growth ; this happens with the greater part of aquatic 

 plants, as Pontederia, Nymphcea, Nelumbium, Hydro char is, Sa- 

 gittaria. Indeed plants are social from causes which are often 

 so trifling, that it is a character of little value, excepting occa- 

 sionally in Geographic Botany. 



Yet after all, this presents but a feeble sketch of the vegetable 

 clothing of the globe. 



[To be continued.] 



III. — On the Occurrence of the Genus Pollicipes in the Oxford 

 Clay, By John Morris, Esq. 



[With a Plate.] 



The fossil species of the family Cirrhipeda, hitherto recorded as 

 British, all belong either to the tertiary or cretaceous series; 

 the pleistocene, marine and crag formations contain remains of 

 species belonging to the genera Acasta, Adna, Balanus, Clitia, 

 Coronula and Bcalpellum. The upper marine, the London clay, 

 and the different members of the cretaceous system contain only 

 species of the genus Pollicipes, so that the addition of two new 

 species of the latter genus from the Oxford clay is an interest- 

 ing fact connected with its geological distribution. 



Pollicipes concinnus. (PI. VI. fig. 1.) 

 Testa subtrigona ; valvulis lateralibus, anticis trigonis apice acumi- 



nato, posticis subtrapeziformibus ; dorsali angustiori acuminata. 



Pedunculo squamulifero, squamulis adpressis subquadratis, trans- 



versim carinatis. 



The compressed state of the specimen prevents the specific 

 characters from being more accurately defined. The anterior 

 valves are trigonal, the posterior somewhat trapeziform ; the dor- 

 sal valve appears to have been narrow and acuminate. The pe- 

 duncle is tolerably well preserved and consists of a series of small 

 closely pressed scales, somewhat quadi-ate in form, each of them 

 being regularly marked by a transverse carinated ridge, present- 

 ing a very neat and uniform appearance. 



The figure (PI. VI. f. I.) represents an interesting group of 

 this species, consisting of three principal individuals, surrounded 



