ACEPHALA. 395 
MacTRA TRIANGULARIS, (Lamarck); Anim. sans Vert., vi. 103. 
Encycl. Meth., pl. 253, f. 3, a b ce. 
From a series of specimens, I am able to trace this large species to 
the Lamarckian name given to a specimen only an inch in diameter, 
having at that stage a depressed, triangular form, very greatly differ- 
ing from the ovate form it afterwards assumes, being then nearly 
of the form of M. solidissima. The delicate, crowded furrowing of 
the young shell becomes coarse; and the fine dewy mottlings be- 
come reddish-brown blotches, and it ought to be called M. lentiginosa. 
Some of the specimens are marked Feejees and some New Zealand. 
The former is more probably the true locality. 
Lurraria Maxima (Middendorff ). 
Testa magnifica, ventricosa, ovato-rotundata, antice rotundata, postice 
sub-triangularis, truncata, valdé hians, concentrice undulato-striata, 
epidermide luteo-viridi (post costam medianam radiatim corrugato) 
induta ; umbonibus tumidis, incumbentibus, attigentibus : cardo val- 
dus; fovea lata, oblique triangulari ; dente cardinali crasso, erecto, 
plicato, basi appendiculato ; dentibus laterahbus compressis, conspt- 
cuis: interior calcarea; sinu siphonal linguiformi, dimidiam longi- 
tudinis teste attigente. 
Lutraria maxima, MippENDortrF ; Beitrage zu einer Malacol. Ros- 
sica ; abth. iii. p. 66, tab. xix., f. 1-4 (1849). 
Lutraria capax, Gou.p; Proceed. Boston Soc. Nat. Hist., i. 217. 
May 1850. Expedition Shells, 76. 
Snett large, capacious, rounded-ovate, rather light and thin, nearly 
equilateral, rounded anteriorly, somewhat triangular posteriorly, and 
at its point, where is a large oval opening. The surface is coarsely 
undulated concentrically, and covered with a coarse, yellowish-green 
epidermis, which, posterior to an indistinct rib running from the apex 
to the middle of the base, is more closely adherent and corrugated, so 
as to exhibit numerous delicate, darker rays. The beaks are tumid, 
and come in contact with each other. Hinge strong, with a large, 
broad, obliquely triangular fossa, a solid, erect folded tooth, with an 
acute appendage at its base, near the point of the beak. Lateral teeth 
