112 THE NAUTILUS. 



shorter tlian in the Califoniian and the basal margin much more pro- 

 duced. 



It may be noted that all the figures, including that of Reeve in the 

 Iconica (Lucina pi. iii, fig. 12, 1850), represent the Brazilian 

 species. The group is represented by nine species in the Tertiary of 

 the Southern United States and Lower California, from the Clai- 

 bornian up to the Pliocene. It is interesting to find that the Florida 

 Pliocene, P. caloosana Dull, though smaller, has the upraised lunule 

 like that of Brazil; while the Pliocene, P. joannis Dall, of San Juan, 

 Lower California (o[)posite Guaymas), resembles the recent P. 

 xantusi in having the folded lunule, only, in this case, the margin is 

 more deeply infolded and the shell heavier, more elongate-oval, and 

 about one-fourth smaller. It measures 55 mm. in height by 51 mm. 

 in width; P. xantusi, 71 x 6S mm., and P. ckildreni. 86 x 77 mm. 



FURTHER NOTES ON THE SPECIES OF MARTESIA OF THE EASTERN 

 COAST OF THE UNITED STATES. 



BY CHARLES W. JOHNSON. 



Since the publication of my article on the species of Martesia of 

 the Eastern United States, I find I have overlooked two important 

 facts, involving one, and possibly two species. The first is 3Iartesia 

 (Martesiel/a) fragilis Verrill and Bush (Proc. U. S. Nat. Miis., 

 XX, p. 777, pi. 79, f. 10, 1898). For this species the above new 

 subgenus is proposed, " which differs from Martesid in having a 

 well-defined, elongated, median, dorsal plate, posterior to the umbos, 

 in addition to the shield-shaped one over them.'.' This seems to be 

 a typical Martesia for the " elongated median, dorsal plate" (meta- 

 plax) is present in all the species. The description of the shell, 

 " umbonal plate" (protoplax), and the figure would indicate that it is 

 very close to or identical with a small specimen of M. striata Linn. 

 The " specimens were found in a piece of wood floating near Station 

 2565, N. lat. 37° 23', W. long. 68° 8'," about 500 miles off the 

 coast of North Carolina. 



The second and more important omission was kindly pointed out 

 by Dr. Dall, who in a recent letter says: " I read your paper in the 

 last Nautilus with much interest, but I cannot agree with you in 

 regard to the Pholas semicostata of Lea, for which I proposed the 



