1896.] NATURAL SCIENCES OF PHILADELPHIA. 33 



tuiiity has not offered to make excursions to determine this at the 

 right season, and we can only surmise that some of the uniques 

 taken on Verbesina, Bigelovia, etc., will be hereafter found abun- 

 dantly attached to some other plant in the neighborhood. 



The flowers visited are cited in their systematic order, following 

 the arrangement of Eugler and Prantl, as recently adopted in the 

 A. A. A. S. list. The number of known Perdita flowers is 25, of 

 which 13, more than half, are Compositie. Twelve species of flow- 

 ers have furnished more than one Perdita species, the greatest num- 

 ber (12) being from Bigelovia ivrightii. 



It is to be explained in reference to the names used for the flow- 

 ers, that the writer is in favor of using the earliest generic name in 

 every case, when not jireoccupied by a valid homonym ; and also 

 the earliest specific name when not preoccupied by a valid homonym 

 in the same genus. But he is entirely opposed to the practice of 

 ■displacing names because antedated by synonyms, which are not 

 and never were deserving of recognition ; and he does not consider 

 a varietal name invalid because previously used for a different spe- 

 cies, or a variety of a different species, in the same genus. He thus 

 objects to the substitution of Chondrophora for Bigelovia (or Bige- 

 lowia), or of Covillea for Larrea. Likewise of ya.r. jnlosus for var. 

 villosus of Aster ericoides* 



SALICACE^. 



(1). Salix. The willow-frequenting bees at Las Cruces in May 

 are Perdita salicis, P. nnmerata, Andrena salicinella Ckll., 

 Andrena n. sp., Halictus sp., and Prosopis sp. P. salicis 

 abounds, but of numerata only one was taken. 



AMARANTHACEJE. 



(2). Cladothrix cryptantha S.Watson. P. cladothricis abounds 

 on this ; it was rather surprising to find so simple a flower so 

 abundantly visited by a particular species of bee. The genus 

 Cladothrix has cited in the Index Kewensis only two species, 

 both from Western North America. 



NYCTAGINAOE^. 



(3). Wedelia iNCARNATA (L.) Kuntze. Visited by P. pectidis. 

 The Boerhaavia, common at Las Cruces, is not visited by Per- 

 dita; while the large purple mirabilis is, of course, a moth 

 flower, and is visited by Deilephila lineata. 



