(3) FRÉDÉRIC N. WILLIAMS. DU GENRE CERASTIUM. 895 



tion is so faint, that the capsule may be said to be nerveless. This varia- 

 tion in the nervation of the capsule seems to hâve escaped the notice of 

 observera, and has not therefore been ruade use of as a systematic cha- 

 racter. The lateral curvature of the capsule in many species being cer- 

 tainly abnormal as a generic variation is, I think, unusual enough to 

 be considered a character of primary importance in the grouping of 

 species. In the groups subordinate to subgenera, I hâve therefore uti- 

 lized thèse two constant characters of the unequal lateral growth of the 

 capsule and the occasional development of inter-commissural nerves. 



An important character noted by Fenzl is that the seeds of some 

 perennial species are angular (especially in the dried state), owing to a 

 certain extent to the fact that the testa is considerably larger than the 

 nucellus and is lightly attached to it at one point; while in the rest the 

 testa closely invests the nucellus and is not shrunk and angular and (in 

 the early state soon after fertilization of the ovules) vesicularly inflated. 

 Tins character would, however, be difficult to appreciate in small seeds. 

 It will be seen therefore that the fruit- characters not only facilitate 

 the artificial discrimination of species, but establish natural distinctions 

 between them. 



Cerastium is a cosmopolitan genus, and some of its species reach 

 extreme geographical limits. Spécimens of C. alpinum were long ago 

 collected in Spitzbergen, and were sent to Linnseus by bis friend and 

 correspondent Rolander Martin. The species has been recorded from a 

 still higher latitude in North Greenland by Mr. Otto A. J. Ekstam of 

 Stockholm; it is also recorded from Bear Island, Melville Island, and 

 Alaska. Within the tropics species occur at alpine élévations; e.g., C. tri- 

 viale in the Andes of Bolivia at 4500 mètres, C. cœspitosum Tr. et Planch. 

 in the Andes of Ecuador at 4600 mètres, C. africanum in the Cameroons 

 Mountains of German West Africa at 3000 mètres, and near the top of 

 Mt. Ruwenzori in Uganda, C. indicum at above 2000 mètres in Ceylon. In 

 the south temperate zone spécimens of C. triviale were collected in 

 Tristan d'Acunha by Mac Gillivray ('Herald' Exped.), and in Kerguelen 

 Land by Moseley ('Challenger' Exped., 1874), also in Herb. Kew. are spé- 

 cimens of C. arvense brought by Hooker from the Argentine portion of 

 Tierra del Fuego in lat. 5o°, — marking the south limit of the genus. 



