12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, I48 



somewhat pit-like lateral furrows ; the posterior pair longer, directed 

 backward almost to meet occipital furrow, hence defining small, 

 elongate-triangular basal lobes. The glabella reaches maximum ele- 

 vation near the posterior end, at the level of the posterior pair of 

 lateral furrows, where it possesses a small upright spine. Occipital 

 furrow deepened into a pair of small pits laterally, wide medially; 

 occipital ring of moderate length (sag.), extended into a spine incom- 

 plete in all specimens. Cheeks convex, not separated medially by a 

 preglabellar depression, sloping steeply to border furrow in posterior 

 portion. Border lying in a plane, slightly convex, widest medially, 

 narrowing toward the genal angles, possessing a pair of small lateral 

 spines anterior to the level of the front end of the glabella. A series 

 of five or six pairs of low tubercles, as usual in species of Serrodiscus, 

 is visible on the lateral border. The posterior border furrow is 

 directed outward and slightly forward from the axial furrow, thus 

 forming an angle with the posterior cephalic margin and giving the 

 posterior border an elongate-triangular shape. Posterior cephalic mar- 

 gin straight from axial furrow to base of short, outward-directed 

 genal spine. 



Pygidium similar to cephalon in general shape, somewhat more 

 distinctly subtriangular. Axis narrow and long, barely failing to 

 reach the posterior border furrow, fully segmented for the entire 

 length, composed of 12 rings including the terminal one. There is a 

 short, upright spine on each of the first seven axial rings. Pleural 

 regions convex, totally un furrowed. Border furrow deep, border rela- 

 tively narrow, of almost even width. Articulating facet well devel- 

 oped. Border extended downward and inward into narrow doublure 

 forming a series of blunt spines not visible except by removing the 

 matrix under the border ; terrace lines on doublure following the 

 serrated outline. 



Surface of test mostly smooth, except for granules visible in some 

 specimens on the last few axial rings and sometimes on the posterior- 

 most portion of the pleural regions. Length of largest (incomplete) 

 cephalon 18 mm, width 20 mm. Length of largest pygidium 12 mm, 

 width 16 mm. 



The species is named for Dr. John M. Bird who collected the 

 holotype. 



Occurrence. — Collection cs-4. North Chatham. 



Ty/>^j.— Holotype : U.S.N.M. 145987. Paratypes: U.S.N.M. 

 145988. 



