as distinguished from the Symplocaceae. 403 



placenta, are continuous with as many parietal nervures that run 

 up into the hollow style. The fruit of Pterostyrax is much 

 smaller, scarcely more than one-fourth the size of that oiHalesiUj 

 and its nut is much thinner in substance ; but its structure is 

 quite analogous, leaving little doubt that it has undergone the 

 same peculiar mode of growth and development as that before 

 described in the latter genus. In the only seed-vessel I have 

 seen, the seeds were destroyed by age. The habit of Pterostyrax 

 corymbosum is more like that of Styrax Obassia, its leaves having 

 the same kind of deep sharp serratures : its inflorescence, as in 

 Styrax, is racemose, the racemes being many-flowered, and axil- 

 lary as well as terminal in the young branchlets. Its flowers are 

 smaller than those of Halesia tetraptera, and about one-third the 

 size of those of H. diptera. 



The following generic character has been framed from my 

 own observations : — 



Pterostyrax, Sieb. et Zucc. — Flores hermaphroditi. Calyx 

 parvus, turbinatus, ovario adnatus, margine libero, hie 4-5- 

 dentatus, dentibus acutis, medio nervis decurrenti-carinatis. 

 Petala 4-5, dentibus calycinis alterna, spathulato-oblonga, 

 tenuiter membranacea, sublibera, sestivatione imbricata. Sta- 

 mina numero petalorum dupla, uniseriata, subsequalia, petalis 

 paullo breviora; filamenta late loriformia, membranacea, 

 sublibera, vel basi laxe agglutinata, I-nervia, intus stellato- 

 pilosula, extus glabra; anlherce introrsse, summo filamen- 

 torum omnino adnatse, et iis 5-plo breviores, ^-lobse, lobis 

 discretis, parallelis, rinia longitudinali dehiscentibus. Pollen 

 trigonum, angulis bulla rotunda notatum. Ovarium turbi- 

 natum, semisuperum, dimidium inferius calyce adnatum, hinc 

 post anthesin cito deorsum elongatum, et valde auctum ; dimi- 

 dium superius non augescens, hinc conicum, liberum, immu- 

 tatura, fructum coronans; 1-loculare, imo septulis 4-5 brevibus 

 ad placentam centralem e basi ortam nexis, et cum carinis 

 totidem internis prominulis parietalibus intra stylum per- 

 currentibus continuis, hoc modo breviter 4-5-locellatum, 

 locellis superne apertis, et lobis calycinis oppositis ; ovula ad 

 placentam centralem in quoque locello 2-seriatim affixa, in- 

 feriora pendula, superiora erecta, fere omnia abortientia. 

 Stylus simplex, staminibus longior. Stigma clavatum, summo 

 4-5-denticulatum. Fructus oblongus, siccus, indehiscens, 

 4-5-alatus, alis interdum fere obsoletis, apice summo per- 

 sistente ovarii coronatus ; structura Halesia omnino similis, 

 sed minor, et substantia nucis tenuior. 



Frutices Japonic^ habitu Styracis, pilis stellatis tomentellis ; 

 folia alterna, acuminato-ovata, argute glanduloso-serrulata ; 



26* 



