264 ON SOUTH-AMERICAN APOCYNACEA, 
when the latter is restricted within its legitimate limits. One of the features, almost 
peculiar to it, is the double coma of its seeds, which suggested its generic name. The 
characters of Heterothriz may be thus summarized :— 
HETEROTHRIX, Müller: Echites, in parte, auct. Sepala subparva, lanceolato-ovata, subæqualia, intus 
squamulis paucis minutis, acutis subalternis munita. Corolla mediocris, hypocrateriformis; fubus 
cylindricus, medio subconstrictus, et ibi staminigerus, fauce glaber et haud plicatus ; segmenta dola- 
briformia, dextrorsum convoluta.' Staminas, in constrictione tubi inserta, inclusa ; filamenta brevia, 
lata, rigida, extus glabra, intus pilosula; anthere anguste oblong, apice membrana obtusa termi- 
natz, imo brevissime et obtuse bilobæ. Discus suburceolatus, fere ad basin in lobos 5 obtusos imo 
connatos fissus. Ovaria 2, distincta, obtuse ovoidea, disco fere zquilonga ; stylus gracilis; clavun- 
cula incrassata, conice pentagona, imo indusiata ; stigmata 2, parva, obtusa, terminalia. Folliculi 2, 
teretes, subulatim tenues, vix torulosi, erecti; semina plurima, oblonga, apice truncata, subcom- 
pressa, costatim striata; coma apicalis, duplo longior, e pilis numerosis rigidiusculis, in seriebus 2 
dispositis, quorum exteriores quintuplo breviores. 
Frutex Brasiliensis, subhumilis, r ; rami validi, breves; folia opposita, rotundo-ovata, imo 
subcordata, apice emarginata, rigidiuscula, brevissime petiolata; cyma lateralis, pedunculata, apice 
capitato-densiflora; flores breviter pedicellati. 
1. HETEROTHRIX PYCNANTHA, Müll. Fl. Br. xxvi. p. 133, tab. 40: Echites pycnantha, Steudel, Nomenc. 
p. 540; A. DC. Prodr. viii. p. 469; Benth. & Hook. Gen. ii. p. 724: Echites densiflora, Pohl, 
Steudelm. Bot. Zeit. 1841, p. 56 (non Bl). In Brasilia, prov. Minas Geráes, ad Serra do Pinheiro: 
non vidi. 
A low bushy tree, 3-4 feet high, with very stout rigid branches, and branchlets 
33 lines thick, costate-striate, pubescent, with axils 1i in. apart; leaves orbicular or 
ovate, shortly cordate at the base, emarginate and mucronulate at the summit, rigidly 
chartaceous, fuseous and densely pubescent above, with about 12 pairs of subdivergent 
nerves, with others intermediate, all anastomosing and conjoined near the margin, 
sericeo-tomentous beneath, 31 in. long, 24 in. broad, on petioles (the depth of the sinus) 
1 line long; the upper leaves smaller; the peduncle erect, lateral at the nodes, bare at 
its base for 13 in., supports a globular head of flowers 2 in. in diameter, on closely 
approximate pedicels 13 line long; sepals somewhat acuminate, 2 lines long, } line broad; 
corolla salver-shaped, in all 1 in. long; tube cylindrical, 8 lines long, shortly constricted 
in the middle; segments broadly dolabriform, with dextrorse ias 4, lines long, 
3 lines broad; the filaments, seated in the constriction of the tube, are 2 line long; the 
anthers 24 lines long, cohering in a cone; the slender style 4 lines Leien follicles 2, 
terete, 33 in. long, 14 line thick; the seeds 2 lines long, $ line broad; coma croceo- 
rufescent, erect, consisting of dense hairs, the inner series 5 lines long, the outer series 
1 line long. 
2. HETEROTHRIX Van HEURCKEII, Müll. in Pl. nov. Van Heurck. p. 164: Mandevilla sp., Benth. & Hook. ` 
Gen. Plant. ii. p. 727: non vidi. 
I have not seen the detailed description of this species; but it would seem to differ 
from the foregoing in little else than that the more slender nerves and transversely 
parallel veins are more numerous and closer. 
The authors of the * Genera Plantarum’ (J. c. supra) refer these plants to Mandevilla ; but 
this opinion cannot be accepted, because the plants differ widely in nearly every respect. 
