34 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.54. 



a slender, long clavicle. Hinge short and arching. The corruga- 

 tions are present on the umbonal slopes and the slight broad depres- 

 sion across the center is like N. corrugatus. 



Formation and locality. — Same as N. ladon. 



Remarks. — A specimen presenting this form has been seen in the 

 shales of the Edmunds formation at northern end of Straight Bay 

 (loc. No. 1443 D 7). 



Type-specimen.—C&t. No. 62872, U.S.N.M. 



NUCULITES LICHAS. new species. 



Plate 11, fig. 20. 



The third species, Nuculites lichas, is still closer in general form to 

 N. corrugatus, but the front is higher, more broadly rounded, the 

 back low and not projecting above the hinge, the posterior end is 

 probably like that of N. corrugatus but low and flattened. Several 

 wrinkle-hke lines radiate backward from behind the beak, which in 

 the specimen are nearly as prominent as the long, slender backward 

 trending clavicle. 



Formation and locality. — Same as N. ladon. 



Remarks. — It would be misleading to speak of these three forms 

 as varieties, in the biological sense, of N. corrugatus. There is no 

 reason to suppose that the shells of the species N. coirugatus varied 

 in these ways in life. Nor is it any more correct to call them varie- 

 ties of N. hattus to which in their present state they have close resem- 

 blance. 



Strictly speaking, they are metamorphic species, real for the pale- 

 ontologist, but mythical, as are their names, for the zoologist. 



Type-specimen.— Csit. No. 62873, U.S.N.M. 



NUCULITES SUBPLANUS, new species. 



Plate 11, fig. 17; plate 12, fig. 8, magnified. 



Shell thin, transversely elliptical, compressed, somewhat naiTowed 

 behind, basal margin regularly and gently roimded with a slight imde- 

 fined constriction near the posterior end. Beak low and broad, ris- 

 ing but little above the hinge line, terminating a Uttle in front of 

 center. General surface depressed-convex, umbonal ridge low, unde- 

 fined, and with a slightly depressed furrow in front of it. Surface 

 crossed by fine concentric lines, the posterior umbonal ridge and slope 

 crossed by fine radiating hnes. Clavicle short but distinct, hinge 

 with crenulate teeth. 



The dimensions of the type-specimen are 20 by 12 mm., making 

 the height 60 per cent of the length, which is within the limit already 

 set for specimens of iV. corrugatus. 



Formation and locality. — Edmunds formations: Gray shales, shore 

 of the Httle cove in northeast part of Crowe Neck, openmg into north 

 end of Straight Bay, Trescott Township (loc. No. 5.33.8 B). 



