Legfentl. g. Umboiial wjirs. 



1. Lateral s<-ai's. 



k. Sliddle laterals. 



j. Anterior laterals. 



1. Outside latei-als. 



X. Concrete latei'als. 



h. Central scars. 



PLATE I. 



c. Concrete centrals, 

 i. Transmedian scars. 



d. Carilinal area. 



s. Median seiitnni._ 

 s'. Latei'al septa, 

 vs. Vascular trunks. 

 V. Vasculai- branches. 



LINGULA, Bruguiere. 



- - Glossi.\.\, Phillips. 



I'age l."i. 



LiNCxULA (Glossina) ACUMINATA, Coiiracl. 



Fiir. 1. A i)ediele- valve from which most of the sulisfance of the shell has been exfoliated, presenting' a 

 c.'isc (if the internal surface,. which retains the inijiressions of the tine radialinf^, and coai-ser, 

 more distinct, concenti'ic lines. The thickness of the shell-sulistance and the undulating char- 

 acter of its laminae, is .shown on file margin;il portion of the figure, but no traces of muscular 

 impressions are discernilile. X 2. 



Fig. 2. A lirachial valve of the same species, from which the shell is partially exfoliated. X '-i. 

 Calciferous sandstone. SamfiM/a, iV. 1'. 



LiNGCLA (Glossina) iuciniformis, Hall. 



Kig. :i. .\ ]iedicle- valve (?) from which the outer layers of the shell are somewhat (sxfoliated ; showing the 

 strong median I'adii, which are evidently moi'e distinctly developed on the intei'ioT' than on 

 the exterior of the shell. X 3. 



Trenton limestone. MiddlfTiUr, JSf. Y. 



LiNGULA Vanhounii, Miller. 



Fig. 4. Tlie interior of a pedii'le-valve ; showing the undifi'erentiated lateral iiiu.sciilar scars, and the low, 

 median sejitum. X 3. 



Hudson River group. Cinriimaft, OIi'hi. 



LiNGULA Phocteri. Uii'ich. 



Fig. .'). The brachial valve of an internal east : showing the concrete laterals (x), the anterior laterals (j), 



and the septum (s). X 1.5- 

 Fig. 13. The o)>poi3ite valve of the same specimen ; showing the progressive lateral and median impres- 

 sions (septum) and the vascular markings. X L5. 



Hudson River' group. South (hmiKjUin, Ki"ii.tiicky . 

 Fig. 7. An internal cast of a bi-achial valve ; showing the lateral scai's and long median septum. X 2. 

 Hudson River !gi-oup. Chic'ninali. Ohio. 



LiNGULA Philomela, Billings. 



Fig. S. A peilicle-valve ('.). imperfect in the umbonal i-egion : illustrating one extreme of outline attained 

 liy shells of this g(inus. Natural size. 



Trenton limestone. FlorencevUh , Houxird munty. Imoa. 



LiNGULA LAMELLATA, Hilll. 



Figs. (I, 10. F,xternal and internal views of the same specimen. Natural si/e. 

 Niagara grcnip. Tjockport, N. Y. 



LiNGULA CUNEATA, Coilfiul. 



Fig. U. An internal cast of the jiedicle-valve ; .showing the broad, low, median septum and the faint lateral 

 scars. X 2. 



Fig. 12. The brachial valve, with an ill-detiru'd muscular scar and traces of the vascular sinuses. 



Medina sandstone. Albion, N. Y. 



