112 DEVONIAN FAUNA. 



Anterior muscle-scar small, circular, situated marginally immediately under the 

 anterior end of binge-margin. 



Size. — Height 58 mm., length 78 mm., depth 40 mm. 



Localities. — There are three specimens from Marwood in the Museum of 

 Practical Geology, two of which were figured by Phillips ; and several from 

 Marwood in the Woodwardian Museum. 



Remarks. — This species is remarkable for its short hinge, and its peculiar 

 trigonal, wedge-like form. The few specimens known are very various in shape, 

 but appear to be probably different from the common and equally variable 

 Cuculldea by which they are accompanied. Phillips observes, " The extreme 

 depression of this shell (compared with the former) is remarkable, and does not 

 depend on distortion or pressure, but it is very uncertain how much must be 

 allowed to accidental or local variations of form." 



2. Genus — Parallelodon, Meeh and Worthen, 1866. 



1. Parallelodon pygm^us, Whiteaves, var. infans, var. nov. Plate XII, figs. 4,5. 



1892. Maceodon ptgm^us, Whiteavess. Cont. Canad Pal., vol. i, pt. 4, p. 299, 



pi. xxxix, figs. 2, 3. 



Description. — Cast minute, convex, serai-oval, transverse, and very oblique. 

 Umbo small, acute, oblique, tending forward, distant, elevated a little above the 

 hinge, and situated between the anterior one-third and one-fourth of the length. 

 Hinge apparently broad and massive, equal (or very nearly so) to the greatest 

 length, bearing two very long and strong obliquely transverse teeth. Anterior 

 margin very narrow, obliquely convex. Inferior margin very long, obliquely 

 straight in front, roundly convex behind. Posterior margin almost vertical, 

 broadly convex. Contour of cast concave on hind wing, roundly convex on the 

 line of greatest depth from umbo to postero-inferior corner, depressed behind the 

 line from umbo to antero-inferior corner, and very deep in front. Shell- 

 structure very massive. 



Size. — A specimen measures 2"5 mm. high by 3'5 mm. long. 



Localities. — In the Barnstaple Atheneum is a specimen on the same slab as 

 Creni])ecten auritus from Bradiford, and in the Porter Collection are two specimens 

 on a slab from Poleshill. 



BemarJcs. — Only the cast of this minute shell is known. It appears evidently 

 to belong to the genus Parallelodon. 



