2;5() 



iuid jiroiiiineiit : forMiiieii limited bcdow liy \vell-devel()[ie(l del- 

 tidial plates. Braehidinin coiisistinu- of a loop bent back 

 upon itself, the juncture of the branches occui-rinu' a little 

 below the plane of their origin. 



Cryptoxella I'LAxiRosTKis. Hall. (Fig. 147.) (Pal. 

 N. Y., Vol. IV.,p. 397), PI. LXI.) 



Distinguishiiti>' Cliciracters. — Great convexitv of valves; 

 large size of adult ; often truncate front and consequent sub- 



FiG. 147. Cn/j>ti>in'lhf jil(nii,iistn:i. I)orsal. ventral, and profile views of a large, stroiigly- 

 markeil individual ; enlartreineiit of heak of pedicle valve ; dorsal, ventral, and i^rofile views 

 of a smaller and less stroiitjly-niarked individual (from Hall). 



pentagonal outline of valves: angular unil)onal margins of 

 pedicle valve, with Hat or concave faces on either side of the 

 deltidial plates. 



Found in the Encrinal limestone, at Section ~> (common). 

 Doubtful specimens have been found in the shale Ijetween the 

 Encrinal and Pleurodictyum beds. 



Ckyptonelt.a rectirostkis. Hall. (Fig. 1-1-S.) (Pal. 

 N. Y., Vol. IV.. p. 394. PL LXI.) 



Distinguishing- Characters. — Fsually small size: sub-rhom- 



boidal outline; fre(iuently trun- 

 cated front; erect beak, with 

 inflected cardinal margins. 

 Ft)und in the Pleurodictyum 



Fig. 148. Cn/ptonella rectirosMs. Dor- beds. ill A Very 's Creek, a lid OU 

 sal, ventral, and profile views of a speci- i t i lh 



men (from Haio. the Lake bliorc (common j. 



