OF THE COSCINODISCE.^::. 



831 



fereuce. AVithiu the live forms some- 

 times mmieroiis yellow vesicles are seen, 

 as in Gallionella. Diameter of fossil 

 1-1150" to 1-480"; living, 1-1150" to 

 1-8G0". 



C. eccentricns (E.). — Cellules small, 

 disposed in excentric curved lines. KB. 

 pi, 1. f. 9. Common, both recent and 

 fossil. D. 1-860 to 1-430 '. 



3t Cellules in no determinate arrange- 

 ment. 



C. concavus (E.). — Each valve very 

 concave, the two opposite conjoined, 

 forming an entire, A'eiy convex body ; 

 cellides coarse, equal, not radiating. 

 EM. pi. 18. f. 38; GDC. pi. 2. f. 47. 

 Virginia. Cellules 4 in 1-1200". An 

 Afi'ican variety has twice as many. = 

 Melosira cribrosa, Sm ANH. xix. p. 11, 

 pi. 2. f. 15. 



C. heteroporus (E.). — Cellules hex- 

 agonal, smaller at the margin and centre, 

 intermediate ones largest, imequal. KA. 

 p. 123. Beimuda deposit. D. 1-360". 

 This species may be recognized by the 

 smaller marginal and central cellules and 

 the very imequal intermediate ones. 



C. minutus (Kiitz.). — Disc nearly 

 smooth, margin with punctated rays. 

 D. 1-1416". KB. 1. 1. f. 14. CuxhaveA. 



C. minor (E.). --Margin smooth ; disc 

 irregularly and densely celluloso-punc- 

 tate. Fossil, Sicily and Virginia ; alive, 

 Europe and America. E. /. c. Not C. 

 mifior of SBD. 



C. Jlavicans (E.). — Disc small, with 

 very fine non-radiating cellules, yellow 

 by transmitted, but white by reflected 

 light. KSA. p. 122. Peru and St. Do- 

 mingo. 



C. labyrinthus (Roper). — Disc divided 



by dotted lines into large, irregular, hex- 

 agonal, minutelv dotted spaces ; puncta 

 15 in -001". Pto'MJ. \d. p. 21, pL 3. f. 2. 

 Pembrokeshu-e. This species has some- 

 what the aspect, under a low power, of 

 a finely marked specimen of C. eccen- 

 tricns, but difters in the absence of a 

 spinous margin, and in the large and 

 irregularly shaped hexagonal spaces 

 ^vdthout any clearly defined margin (Ro.). 



Doubtful or imperfectly hioivn Sjiecies. 

 C. cinctus (K.). — Rim with inter- 

 rupted radiating strise; cellules of disc 

 crowded in the centre, the others scat- 

 tered, remote. KSA. p. 122. C. Patina, 



B. AJmer. Jour, of Science and Arts, 

 1842, pi. 2. _f. 13. Alive, Cuxhaven; 

 fossU; Virginia. Diam. 1-324". Ehren- 

 berg refers the Virginian specimens to 



C. minor. 



C. oralis (Ro.). — Valves oval, brown- 

 ish in balsam, with finely-dotted radi- 

 ating lines and no distinct imibilicus. 

 Ro MJ. vi. p. 22, pi. 3. f. 4. Pembroke- 

 shire. Markings very delicate and in- 

 conspicuous, (v. 78.) 



C. punctulatus (Greg.). — Disc marked 

 with very fhie and obsciu-e lines, the 

 whole surface sparsely punctate. Lam- 

 lash Bay. GD. p. 28, pi. 2. f. 46. 



C. nitidus (Greg.). — Disc marked with 

 distant and irregularly radiant granules, 

 larger towards the centre ; margin striate, 

 striae about 16 in -001". Lainlash Bav. 

 Greg. /. c. p. 27, pi. 2. f. 45. (viii. 18.)' 



C. cervinus (Bri.). — Disc minutely 

 punctate, pimcta scattered ; centre con- 

 vex. Diam. -0054" to ■0086". = B:i/alo- 

 cliscus cervinus, Bri J31S. viii. p. 95, pi. 5. 

 f. 9. Arctic regions. 



G^iiTis ENDICTYA (Ehr.). — Fnistiiles dLsciform, simple or forming short 

 filaments, closely ceUulose, in front view with a middle furrow, having on 

 each side crowded parallel series of cellules. Kiitzing places its only species in 

 Coseitiodiscus ; but we think that it is much more nearly allied to Orthosira. 



Endictya oceanica (E.). — Disc with 

 close cellules and a dentate rim. (v. 70.) 

 EM. pi. 35 A. 18. f. 6, 7. = Orthosira oce- 

 anica, Bri JMS. viii. p. 96, pi. 6. f. 16. 

 Common in Peruvian guano. Some- 



times the cellules of the disc are almost 

 concentric in their arrangement, 7 in 

 1-1152". Diam. 1-528". This^ form is 

 probably identical with Coscinodiscus 

 concavus and Melosira cribrosa. 



Genus CRASPEDODISCUS (Ehr.). — Fnistules simple, disciform; disc 

 cellulose, Tvdthout striae or septa, but having a broad, well-defined, tumid 

 border of a diflferent structure from the centre. Craspedodiscus has the habit 

 of Coscinodiscus, with which Kiitzing united it. It diff'ers from Coscinodiscus 

 Umhatus, and similar forms, by its margin, which does not form a mere rim, 

 but a broad border of a dififereut structiu?e, separated from the centre by a 

 distinct furrow or well-defined line. 



