K6 DESMID8 OF THE UNITED STATES. 



C. Broomei, Thwaites. Plate XVII, fig. 6-9. 



Usually as long as broad, sometimes slightly longer, 

 obtuse-quadrangular; sinus narrow linear; semicell oblong- 

 quadrangular, twice as broad as long, angles, inferior and 

 superior, obtusely rounded, base plane, end broadly truncate 

 and often slightly retuse, or moderately convex ; end and side 

 view evidence a distinct central inflation ; cytioderm rough 

 with pearly granules arranged in subereet lines. 



Diameter 80-45 u. 



Appears to be entitled to the term "common." 



C. PSEUDOBBOOMEI, Wolle. Plate LI, fig. 36. 37. 



This new Bpecies is in all its details of structure like the pre- 

 ceeding, but entirely devoid of a central inflation. 

 Diameter 30-45 u. 



Wood Lake, northern New Jersey, furnished scores of 

 specimens of this species the past Summer, 1883. 



C. biretum, Breb. Plate XVII, figs. 1. 2. 



Subquandrangular or polygonal ; a deep constriction forms 

 a narrow linear Bin us ; semicells obtuse-quandrangular, with 

 subreniform base, and end broad, Bubplane-convez, dilated ; 



cytioderm rough with pearl-like granules arranged in con- 

 centric series j end view shows a prominent central swelling. 

 Diameter oo-G0 //. 



Rather rare, singly among other Alcjic, but occasionally in 

 quantities. Had a cluster of Oedogoniwn from a sluggish 

 stream near Closter, X. J., literally covered with specimens of 

 this species. 



C. caelatum, Ralfs. Plat. XVIII, figs. 16, 47, 48. 



Suborbicular, deeply constricted, sinus narrow linear; semi- 

 cells subsemicircular, diameter equal to twice the length ; 

 margins scolloped or broadly crenate, with four crenatures at 



the end, one on each side at the base, and one intermediate 

 between it and the end ; the lateral, basal ones are the largest ; 

 membrane sulcated between the crenatures ; rough with pearly 

 granules; end view oval, somewhat inflated at the middle. 

 Diameter 40 ft., more or less. 



A distinct species which turus up frequently in smaller 

 numbers. 



