282 



xvi., 2nd part, p. 145) he regards it as a doubtful species. This 



I have not seen. 



The latest addition to the species is to be found in Hemsley's 

 Botany of Central America, (Vol. lii., p. 162) published in 1883, 

 where Caiya Mexicana, Engelm., is described from Dr. Engel- 



5" mann's manuscript, based on Parry and Palmer, No. 834}^ from 



mountains near San Luis PotosI, at an altitude of 8,000 

 feet After a careful examination of the materials preserved in 

 the Philadelphia, Washington, Easton and New York Herbaria, 

 I have not been able to reduce any of the species found in recent 

 writings. I would, however, arrange them a little differently 

 than has hitherto been done in order to bring out more natural 

 alliances. It is a very perplexing genus, and I am not sure that 

 any arrangement would be wholly satisfactory. The salient 

 characters of one species are liable to appear in others, sometimes 

 with considerable prominence, rendering it troublesome to refer 

 certain individuals even when they are well known. Single her- 

 barium specimens are, naturally, even more perplexing. My 

 present notion of them is as follows : 



(A.) Subgenus Pacania, Raf , Alsogr. Amen, p. 65. Nut 

 cylindical or oval, smooth, two-celled ; staminate catkins in 

 lateral, nearly sessile fascicles at the summit of shoots of the pre- 

 ceding year. 



1/ (t.) H. Pecan (Marsh.) (7?/^/^;/^ P^r^;/, Marsh., Arb. Amer 

 p. 69; (1785); Juglans olivcEforjuis, Michx., Fl. Bor. Amer., 

 ii., 192 ; (1803) ; Carya oliv(^fonnis, Nutt.) 



(la.) H, 7>;i-^;/^, LeConte, Proc. Phila. Acad., i853,p. 402. I 

 am not at all satisfied that this can certainly be referred to the 

 ordinary Pecan. There appear to be no specimens extant to 

 illustrate the description, but the characters given would indicate 

 that this may very well be a different species or variety, and this 

 supposition is strengthened by the statement that the leaves of 

 the Pecan are fully formed before those of the tree in question 

 show the least sign of unfolding. 



(B ) Subgenus EUHICORIA. Nut more or less compressed 

 (except in the last species), ovate, obovate, oval, or nearly glob- 

 ular; staminate catkins in threes on a common peduncle at the 

 bases of shoots of the season. 



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