456 DESCRIPTION OF IPoli/gaHtrica. 



BiDDULPHiA jf;«7("//6'//rt (Ehr.) — Quadrangular, compressed, with from 

 three to five small obtuse lateral processes. In the sea, near Cuba ; and 

 fossil in the chalk marl of Greece. Diameter l-290th. It is also 

 found on the English coast ; and Mr. Ealfs has described it thus : — 

 " Frustules distinctly reticulated; surfaces lateral, with one or three 

 rounded projections between the angles, and marked with a few 

 distant striae, which appear to arise from the depressions between the 

 projections. (P. 13, f. 46, 47, 49, and 50.) 



"It is brownish when recent, and becomes paler in dry- 

 ing. Filaments elongated, attached ; angles of frustules rounded, 

 and occasionally constricted at their base. There is tio con- 

 striction at the junction of the lateral portions with the centi'al 

 one, as occurs in B. aio'ita.'' Ehrenberg enumerates three to five 

 lateral processes ; Ralfs one to three ; but this apparent discrepancy 

 is removed by the circumstance, that the latter observer does not 

 count the angles of the frustules as lateral processes, which Ehren- 

 berg does. 



B. aurita (Ralfs) = Odontclla aurita (Kiitz.) — Frustules (testules, 

 E.) very minute, quadrilateral, cellulose, structure indistinct, lateral 

 portions without striae, constricted at their junction with the central 

 one, and destitute of striae. 



" This species differs from B. pidchella, in the same manner as 

 Isfhm'a enervis does from /. oUiquata, viz., in the absence of striae. 

 But it also differs from B. pulchelh, by its smaller size, obscure reti- 

 culations, and by its constrictions." 



B, (?) limata. — Smooth, with three lobes on the side, slightly 

 curved, limate, and with subacute horns Diameter 1 -864th. 



B. (?) Gigas. — Large, very turgid at the centre ; rough, without 

 distinct granules, laterally presenting five segments, having a large 

 oblong apertiu'e in the tapering apex of each side, which, therefore, 

 is tubular. (?) Diameter 1-1 44th. Bermuda. 



B. (?) ursi'na. — Large, turgid, not cellular ; sides furnished with 

 hairs ; without constrictions ; central area smooth. Diameter 

 l-192nd. Docs it belong to Ilemtaulii.i. (?) Its haiiiness is re- 

 markable, and approaches it to Tetrachceta. It is described by Dr. 

 Bailey. 



