1873.] i 363 [Morse, 
these statements of Forbes and Hanley, and expresses his belief in 
their correctness. In speaking of their peculiar asymmetry induced 
- by this byssal modification, he aptly calls them the Pleuronectes 
among Mollusks. 
In the year 1847, Steenstrup presented similar views before the 
Royal Danish Academy.' And in the same year, during the meeting 
of the Scandinavian Naturalists in Copenhagen, he made a similar 
communication, which was published in their Report for that year. 
On both occasions he militated against the suggestions of Owen, 
Agassiz, Deshayes, and other naturalists, who considered Anomia as 
-a connecting link between the Lamellibranchiates and the Brachio- 
-pods. He showed that Anomia was not so abnormal as was generally 
supposed, and that the foramen in Anomia had no correspondence to 
- the opening of the valve in Terebratula, but, on the contrary, was 
-homclogous to the notch in Pedum, Pecten, and certain other bivalve 
Mollusks, and that the plug in Anomia was simply a calcified byssus, 
and that it passed through this notch and held the shell fixed to some 
object. He showed also that the muscle attached to this plug was a 
foot muscle, corresponding to the muscle which goes to the sheath of 
the byssus in certain other Lamellibranchs; and concluding with the 
statement that the Terebratula and all the Brachiopods might neces- 
sarily be considered as not only widely removed from the Lamelli- 
branchiates, but as having no sort of relation to the Mollusca ai all. 
Last year, in a brief examination of the early stages of Anomia, I 
had the pleasure of amply confirming the predictions of Forbes and 
Steenstrup, namely, that the plug in Anomia represented simply a 
modified byssus. 
The following extract is taken from my short paper on the Rela- 
tious of Anomia.? ‘The smallest specimens examined are quite 
orbicular, the upper or left valve is very tumid near the nucleus, the 
lower, or right valve is flat, and somewhat smaller than the upper 
valve. The foramen, or sinus, is not closed, but opens on the anterior 
border of the shell. The chief point of interest, however, is seen in 
the nucleus, or that portion of the shell first formed, when the ani- 
mal was free and roving. ‘This early condition of the shell is dis- 
tinctly marked at the beak in both valves. It is yellowish in color, 
and marked with numerous, very regular concentric lines of growth, 
while the remaining portion of the shell is colorless, or white, with 
1 Seethe Proceedings for that year, pp. 74, 78. 
2 Proc. Boston Soc. Nat. Hist. Vol. xIv., p. 152. 
