TRoi'inoi.Ki'i'us Facna aj- Canandahjua Lark, N. Y. I-V) 



Pedicle 0/>c/iino-. — The deltidial i)lates of very young individuals 

 first apjjear as narrow pieces on either border of the delthyrium and 

 begin to coalesce along the median line where the specimen is about 

 3 mm. in length. At this same stage the pedicle begins to encroach 

 upon the ventral beak. In adults the i)edicle opening is rather large 

 and circular, and there is a cylindrical tube extending from the opening 

 forward into the umbonal cavity. The deltidial plates are strong, 

 convex and united along the median line. The dorsal beak is some- 

 what rostrate and extends into the anterior end of the delthyrium. 



Muscle Scars. — The scars of the muscles are not deeply impressed. 

 In the dorsal valve there are two diverging raised lines which extend 

 about one third the distance to the front. Between them is a longer 

 median septum which bifurcates at its anterior end. }jetween the 

 diverging lines of the posterior set are two oval adductor scars which, 

 in some specimens, are fairly plain. Outside of them are two larger 

 anterior adductor muscle scars whose limits are faint. 



In the ventral valve under the umbo there is a large triangular ped- 

 icle muscle scar. The adductor scars are narrow and elongate. The 

 limits of the diductors could not be made out. 



Fig. 35. Emiella linckhoii Hall ; part of the loop of an adult specimen. X 8. 

 Fig. 36. Centronellifonn stage of the loop. X ^• 



Flc. 37. Side view of specimen shown in Fig. 36; shell broken away to show 

 the loop. X 16. 



BracJiidiiiiii. — The smallest specimen retaining the brachidium, 

 and the only one in which the loop is complete, is about 4 mm. in 

 length. The loop extends about half the distance to the front of the 

 valve. The primary lamellaj run sharply upward and forward and the 

 anterior lamellae run about parallel to the floor of the valve, meeting 

 in the front in an acute angle. As the two lamella; approach each 

 other they become wider and, when they join, there is also a ])oint 

 directed backward. This is evidently an immature loop, and differs 

 much from that of the adult. It agrees with the centronelliform stage 



