OF THE CH^TOCEEE^. 



863 



This species, in its living state, is in- 

 vested with a mucous covering, and is 

 scarcely, if at all, silicious, — a circum- 



stance wliicli has caused many doubts 

 as to its diatomaceous nature. 



Genus ATTHETA ("West). — Frastules compressed, annulate ; annuli inde- 

 finite ; valve elliptical-lanceolate, ^dth a median line ; angles spinous. The 

 true position of this genus is doubtful ; but, from examination, it appears to 

 approach nearer to Cheetoceros than to any other genus excepting Striatella, 

 from which, however, it is easily distinguished by the spinous angles and ab- 

 sence of stipes. 



Attheya decora (West). — Annuli 12 

 to 28 ; septa alternate ; valve with me- 

 dian line and central nodule. West, 



TMS. ^-iii. p. 152, pi. 7. f. 15. CressweU 

 Sands, Drmidge Bay. (vni. 35.) 



Genus BACTERIASTRUM (Shadbolt).— Frustules awned, united into a 

 jointed, conferva-like, cylindrical filament; valves discoidal, with marginal 

 radiating awns. Bacteriastrum agrees with ChEetoceros in its filamentous 

 character and in the presence of awns, but differs from it in having the awns 

 of its discoidal valves marginal and radiant. Marine. Stomachs of marine 

 animals, &c. 



Bacteriastrum furcatum (Sh.). — 

 Awns smooth, much elongated, forked. 

 =Acthnscus sexfurcatiis, ERBA. 1854, 

 p. 237 ; EM. pi. 35 b. 4. f. 15 ; A. hisepte- 

 nari'M, E. ; A. hisoctonarius, E. Atlantic. 

 The awns vary in number and in the 

 length of the forked portions, (yr. 26.) 



B. curvatinn (Sh.). — Awns simple, 

 elongated, smooth, symmetrically curved 

 in one direction. 



B. Wallichii (Ealfs). — Valves more or 

 less cup-shaped, with 4 to 12 smooth, 

 simple, divergent awns. = Chcstoceros 

 Bacteriastrum, Wallich, TMS. \'iii. p. 48, 

 pi. 2. f. 16, 17. Atlantic. From Salpse. 

 Size extremely variable, (yr. 27.) 



B. noclidosum (Sh.). — Awns siniple, 

 straight, rough. — Awns covered with 

 small protuberances, like a knobbed 

 stick. 



Genus DICLADIA (Ehr.). — Frustules simple, one-celled, bivalved ; valves 

 unequal, turgid, one mostly simple and unarmed, the other two-horned ; 

 horns sometimes branched. 



DiCLADiA Capreoliis (E.).—rOne valve 

 with two stA'les arising from conical 

 bases, and usuallv branched at the end. 

 EM. pi. 35 A. 17. f. 8 ; Bri JMS. iv. pi. 7. 

 f. 53-60. Virginia. Common in guano. 

 The fi-ustide consists of a narrow-linear 

 central portion, projecting at each end, 

 and two turgid lateral valves, which 

 vary greatly in foi-m. Usually the in- 

 ferior one is smaller, simple, and unarmed, 

 but is often bilobed. The larger valve is 

 bilobed ; the lobes manmiiform or conical, 

 each terminating in a style divided at its 



have the upper valve unarmed or simple. 



D. antennata (E.). — One valve, with 

 two simple, setaceous, parallel, acute 

 spines, articulated at the base, like an- 

 tenna ; the other valve unknown. EM. 

 pi. 35 A. 21. f. 9 ; KSA. p. 24. Antarctic 

 Sea. This and the next species were 

 constituted from single fragments. 



D. bidbosa (E.). — One valve with two 

 spines, wliich are divergent at the base, 



connivent above, bidbose and slightly 

 silicate in the middle part; the other 

 valve unknown. EM. pi. 35 a. 21. f. 10 ; 

 KSA. p. 24. Antarctic Sea. 



D. clcdhrata (E.). — Frustide with a 

 rounded, smooth, latticed bodv, and two 

 unequal frontal horns. EM . pL 18. f. 100 ; 

 KSA. p. 25. Fossil. Virginia. 



D. Capra (E.). — Smooth; one valve 

 with two simple spines, the other uni- 

 dentate or imperfectly siib-bidentate in 

 the middle ; central portion naiTow- 

 linear. EM. pi. 18. f. 99. = Periptera 

 Capra, KSA. p. 26. Fossil. Virginia. 



D. Cervus (E.). — Smooth, large ; 

 frontal horns long, branched. =Per?/>^e;*a 

 Cervus, KSA. p. 26. Fossil. Maiyland. 



D. Mitra (Bai.). — Valve having two 

 conical horns coalescing below into a 

 conical base, and bearing branched pro- 

 cesses above. B. in Silliman's Amer. 

 Jom-n. July 1856, pi. 1. f. 6. Sea of 

 Kamtschatka. Perhaps a state of D. 

 Capreolus. 



