DOCOPHORUS. 



[ 269 ] 



DORYPHORA. 



Char. Cells single, straight, much elon- 

 gated, linear, sometimes attenuated towards 

 the ends ; constricted in the middle, ends 

 truncate ; segments usually inflated at the 

 base. 



Rabenhorst includes the species in Pleu- 

 rotcenium. 



Docidiwn, like Closterium, has the termi- 

 nal spaces with moving molecules ; and its 

 vesicles are either scattered or arranged in 

 a single longitudinal row. 



D. truncatum (PI. 14. fig. 38). Seg- 

 ments three or four times as long as broad, 

 with a single inflation at the base ; suture 

 projecting on each side ; length 1-80 to 



D. baculum (PI. 14. fig. 39). _ Segments 

 very slender, with a single conspicuous in- 

 flation at the base, otherwise linear ; vesi- 

 cles in a single series; length 1-111". 



D. nodulosum. Segments four to six 

 times as long as broad, constricted at regu- 

 lar intervals so as to produce an undulated 

 margin; suture projecting; length 1-50". 



Several other species. 



BIBL. Ralfs, Desmid. 155; Pritchard, 

 In/us. 744 ; Rab. Fl. Alg. iii. 141 ; Hobson, 

 Qu. Mic. Jn. iii. 1863, 169 (Bombay). 



DOCOPH'ORUS, Nitzsch A subgenus 

 of Philopterus (Anoplura), distinguished by 

 the small moveable tooth or trabecula in 

 front of the antennae, and the dark lines 

 running from them to the occiput. 



D. communis (PL 35. fig. 5). On Inses- 

 sores. 



D. icterodes. Common on ducks and 

 geese. 



DOLICHOSPER'MUM, Thwaites (P1.8. 

 fig. 6). A genus of ISIostochaceae, allied to 

 Trichormus, Sph&rozyga, &c., established 

 by Thwaites for five British species, from 

 which Hassall has separated one under the 

 name of Coniophytum. Thwaites noticed in 

 this genus that the contents escaped in an 

 undivided mass from the elongated and 

 mostly cylindrical spermatic cells (spo- 

 ranges), which are invariably truncated at 

 the ends. 



D. incequak, Ralfs. Filaments monili- 

 f orm ; ordinary cells at first quadrate, finally 

 orbicular ; vesicular cells large, spherical ; 

 sporanges linear, catenate (Ralfs,^4/m. N.H. 

 2 ser. v. pi. 9. fig. 1). Forming extensive 

 strata, composed of thick gelatinous masses 

 of a deep green colour, on boggy pools ; 

 filaments consisting of 100 to 200 cells. 



D. Ralfsii (Kiitziug). Filaments moni- 

 lit'orm : ^ordinary cells spherical ; vesicular 



cells elliptic; sporanges elliptic or cylin- 

 drical, one or two in each series. Ralfs, I. c. 

 pi. 9. fig. 2 ; Spharozyga Ralfsii, Thwaites, 

 Harvey's Algee, 2 ed. 233. Cylindrospermum 

 Ralfsii, Kiitzing, Tab. Phycol i. pi. 98. fig. 

 7. Forming extensive strata of a velvety 

 rich dark green colour, sometimes verging 

 towards seruginous green, on rivulets and 

 in bogs. 



D. Smithii, Thwaites. Filaments straight, 

 each included in a definite gelatinous 

 sheath; ordinary cells subspherical, com- 

 pressed, about as long as wide ; vesicular 

 cells subspherical, somewhat barrel-shaped, 

 half as wide again as the ordinary cells, 

 puncta very distinct; sporanges cylindrical, 

 very unequal in length, and with the ends 

 rounded and somewhat truncated. Ralfs, 

 I. c. pi. 9. fig. 4. Freshwater boggy pools. 



D. Thwaitesii, Ralfs. Filaments straight, 

 or nearly so ; ordinary cells quadrate ; vesi- 

 cular cells oblong, subquadrate, puncta very 

 distinct; sporanges numerous, cylindrical, 

 with truncated ends, very variable in length 

 (Ralfs, 1. c. pi. 9. fig. 5). Spharozyga Thw. 

 Harvey, Br. Algce, 2. 232. Freshwater or 

 brackish pools. (D. Thompsoni, Ralfs, see 

 CONIOPHYTUM.) 



DOMOP'ORA, D'Orb. A genus of Cy- 

 clostomatous Polyzoa,= Tubulipora, pt., 

 Johnstone. 



2 species; deep water. (Hincks, Pol 481.) 



DONKIN'IA, Ralfs. A genus of Diato- 

 macese, = Amphiprora with decussating 

 striae, but without alas to the valves. 



Pritchard describes 7 species. Raben- 

 horst describes 4 European, and enumerates 

 12 extra-European species. 



BIBL. Pritchard, In/us. 920; Rabenh. 

 Flor. Alg. i. 242. 



DOO'DIA, Brown. A genus of Blech- 

 nese (Polypodiaceous Ferns). Exotic. 



DORIP'YGUS, Brady. A genus of 

 Copepodous Entomostraca. 



Four species ; inhabitants of the branchial 

 sacs of simple Ascidians. (Brady, Copep., 

 Ray Soc. i. 132.) 



DORYPH'ORA, Kiitz. A genus of 

 Diatomaceae. 



Char. Frustules single, stalked; valves 

 orbicular - lanceolate or broadly elliptical, 

 with a median longitudinal line, but no 

 nodules. Marine. 



The valves are furnished with transverse 

 or slightly radiating rows of dots. 



D. amphiceros, K. (PI. 16. fig. 29 : a, side 

 view of frustule ; b } front view ; c, prepared 

 valve.) Valves orbicular-lanceolate or 



