Mr. F. Walker on some new species of Chalcidites. 125 



and in a locality not very distant from mine, the earth from Lough 

 Island-Reavey is almost wholly different, including but few spe- 

 cies, and the more numerous of these found but sparingly in the 

 Lough Mourne deposits. 



The following make up nearly the entire mass of the earth 

 described by Dr. Drummond : — 



Navicula gracilis. Tabellaria fenestrata. 



Himantidium arcus. ventricosa. 



pectinale. 



A few frustules of the following also occur : — 



Surirella splendida. Epithemia zebra. 



Navicula viridis, Cocconema lanceolata. 



The profusion in which N gracilis, H. pectinale and T. fenes- 

 trata occur in this deposit, would lead to the conclusion that the 

 waters of the lake in which it had been found were the drainage 

 of a subalpine district, whose surface was almost exclusively 

 peat, while the Lough Mourne deposit would, even to the phi- 

 lomicros unacquainted with its locality, indicate the neighbour- 

 hood of clear springs, grassy pastures and a low elevation. In 

 this way these minute organisms may afford matter for interest- 

 ing speculation, and when occurring in a fossil state may possibly 

 be made available in the researches of the geological inquirer. 



Wareham, January 10, 1850. 



XV. — Notes on Chalcidites, and Descriptions of various new 

 species. By Francis Walker, F.L.S. 



[Continued from vol. iii. p. 210.] 



— t 

 Caudonia, n. g. , _ « ■ r . 



Fern. Head and chest convex, very finely shagreened : head thick, 

 a little broader than the chest : feelers slender, subclavate ; first joint 

 long, slender ; second cup-shaped ; third and fourtH very small ; the 

 following from the fifth to the tenth successively but slightly de- 

 creasing in length and increasing in breadth ; club long-elliptical, 

 broader than the tenth joint, and more than twice its length : chest 

 spindle-shaped, much developed : fore-chest rather long, having a 

 slight transverse ridge near the hind-border whence it declines and 

 grows narrower and forms a short neck : shield of the mid-chest very 

 long ; sutures of the parapsides distinct for rather more than two- 

 thirds of the length of the chest, but thence quite obsolete ; axillae 

 parted by rather less than one-fifth of the breadth of the chest ; 

 scutcheon nearly conical, with a slight transverse suture towards the 

 hind-border ; hind-scutcheon transverse, but rather large : hind-chest 

 well developed, obconical, declining, with a ridge along the middle 

 and a suture on each side : petiole short : abdomen long-oval, smooth, 

 shining, slightly concave above, rather deeply keeled beneath, some- 

 what broader and a little shorter than the chest ; metapodeon occu- 



