2/6 GENERAL REVIEW. 



species natural hybrids have been discovered. M. Lamotte, 

 writing in 1862, names seven of these hybrids, as follows : 



S. pseudo-arachnoideum, Lamt. ined. 



S. piliferum, Jord. 



S. Jordani, Lamt. ined. 



S. arachnoideo-Boutignianum, Lorr. 



S. Boutignianum-arachnoideum, Loir. 



(= S. rubellum, Lamt.) 

 S. arachnoideo-auvernense, Lamt. 



( = S. Pomelii, Lamt.) " 

 S. auvernense-arachiioideum, Lamt. ined. 



(= S. villosttm, Lamt. olim. ) 



It is singular to find that the "Cobweb House-leek" (S. 

 arachnoideum) is one of the parents throughout the above series 

 of natural hybrids, having in some cases supplied the seeds, 

 and in others again the pollen. S. pseudo-arachnoideum is the 

 most beautiful of the group, having the largest and brightest- 

 coloured flowers ; and M. Lamotte believes that the pollen- 

 parent was S. montanum, the seed-parent being S. arachnoideum. 

 S. piliferum and S. Jordani are probably born of the same 

 parents ; but in these cases 5. montanum is believed to have 

 been the seed-parent. Apart from these natural hybrids, I 

 find no records of any hybridist having experimented with 

 these plants except M. Donkelaar, who, prior to 1862, suc- 

 ceeded in obtaining a hybrid between S. speciosum and S. 

 tabulceforme. Of *$". arboreum there are variegated and purple- 

 leaved forms ; but whether these are seminal forms or sports I 

 cannot say. It appears to me, however, that many of the 

 Sempervivums are susceptible of so great variation that they 

 have repeatedly been described as distinct species ; and in 

 no one species is this fact more marked than in the polymor- 

 phous S. tectorum or "House-leek." In 1866 I obtained 

 seven distinct varieties of this plant from the seed of one cap- 

 sule some of lax habit and green leaves, some little larger 

 than half-a-crown, and of a deep red colour, and others inter- 

 mediate. Indeed, many other Sempervivums seem as variable 

 in this way as are Mammillarias, Haworthias, Gasterias, and 

 other succulents. 



THE CUCUMBER FAMILY (Cucurbitacetz.) 



To this order belong the Cucumber, Cucumis sativus, the 

 Melon, C. melo, and numerous species and forms of Cu- 

 curbita, or Gourds, with which may be classed our Squashes 



