264 ON SOTJTH-AMEEICAK' APOCTNACEiE. 



when the latter is restricted within its legitimate Hmits. One of the features, almost 

 peculiar to it, is the double coma of its seeds, which suggested its generic name. The 

 characters oi Heterothrix may be thus summarized : — 



HetekothkiXj Miiller : Echites, in parte, auct. Sepala subparva, lanceolato-ovata, suLsequalia, iutus 

 squamulis paucis minutis, acutis subaltemis munita. Corolla mediocris, hypocraterif ormis ; tubus 

 cylindricus, medio subconstrictus, et ibi staminigerus, fauce glaber et baud plicatus ; segmenta dola- 

 briformia, destrorsum convoluta. Staminas, in constrictione tubi inserta, inclnsa ; jilamenta brevia, 

 lata, rigida, extus glabra, intns pilosula ; anthera anguste oblongae, apice membrana obtusa termi- 

 natae, imo brevissime et obtuse bilobae. Discus suburceolatus, fere ad basin in lobos 5 obtusos imo 

 connatos fissus. Ovaria 2, distincta, obtuse ovoidea, disco fere aequilonga j stylus gracilis ; clavun- 

 cula iacrassata, 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 piUs numerosis rigidiusculis, in seriebus 2 

 dispositis, quorum exteriores quiutuplo breviores. 



Frutex Brasiliensis, subhumilis; ramosus ; rami validi, breves ; folia opposita, rotundo-ovata, imo 

 svbcordata, apice emarginata, rigidiuscula, brevissime petiolata; eyma lateralis, pedunculata, apice 

 capitato-densiflora ; flores breviter pedicellati. 



1. Heterothrix pycnantha, Miill. M. Br. xxvi. p. 133, tab. 40: Echites pycnantha, Steudel, Nomenc. 



p. 540; A. DC. Prodr. viii. p. 469 j Benth. & Hook. Gen. ii. p. 724: Echites densiftora, Pohl, 

 Steudelm. Bot. Zeit. 1841, p. 56 (non Bl.). In Brasilia, prov. Minas Geraes, ad Serra do Pinheiro : 

 non vidi. 



A low bushy tree, 3-4 feet high, with very stout rigid branches, and branchlets 

 ^\ Itues thick, costate-striate, pubescent, with axUs Ij in. apart ; leaves orbicular or 

 ovate, shortly cordate at the base, emarginate and mucronuiate at the summit, rigidly 

 chartaceous, fuscous and densely pubescent above, with about 12 pairs of subdivergent 

 nerves, with others intermediate, all anastomosing and conjoined near the margin, 

 sericeo-tomentous beneath, 3:| ia. long, 2^ 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 1^ in., supports a globular head of flowers 2 in. in diameter, on closely 

 approximate pedicels 1^ 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 convolution, 4 lines long, 

 3 lines broad ; the filaments, seated in the constriction of the tube, are J line long ; the 

 anthers 2^ lines long, cohering in a cone ; the slender style 4 lines long ; follicles 2, 

 terete, 3^ in. long, 1 J Une thick ; the seeds 2 lines long, f 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 Heueckii, Miill. in PI. nov. Van Heurck. p. 164 : MandevillasTp,, 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 ' {I. e. supra) refer these plants to Mandevilla ; but 

 this opinion cannot be accepted, because the plants differ widely in nearly every respect. 



