388 TESTACEOUS MOLLUSCA. 
f. 28 ... M. striatula, p. 241, t. 24, f. 29 ... M. subramosa, p. 241 
t. 24, f, 30. 
On Myrtitus (p. 243). For additional species consult Zeit. Mal. 
1846, 1847, 1848, An. Nat. 1842, Kuster’s edition of Chemnitz, 
Rev. Zool. Cuv. 1848, 1849 (article Septifer), Krauss’s Sud-Af. 
Mol., J. Conch: 3, 4, Proc. Bost. 3, 4, D’Orb. S. Am. and Cuba 
Shells. 
Mytilus hirsutus, p. 244, t. 24, £32 ... M. granulatus, p. 246, 
t. 24, f. 33 ... M. strigatus of Hinds’ MSS." p. 251, t. 24, f. 34 ... 
M. (Dreissena ) leucopheatus, p. 251, t. 24, f. 31. 
On Pryna (p. 251). See, likewise, Ph. Sic. 2, D’Orb. S. Am., 
Proc. Bost. 8, Zeit. Mal. 1852. 
Pinna saccata, p. 2538, t. 24, f. 85 ... P. atropurpurea, p. 255, 
t. 24, f. 36. 
On CRENATULA (p. 256). See, likewise, Schrift. Berlin. Gesel. 2, 
Beschaft. Berlin. 3, Savigny’s Egypt, Mol. pl. 12, and Zeit. Mal. 
1851. 
On Perna (p. 257). See, likewise, Krauss’ Sud-Af., Wieg. Arch. 
1837, Proc. Bost. 2, 3, and D’Orbigny’s Cuba Shells. 
Perna costellata, p. 259, t. 24, f. 37. 
Malleus albus, p. 260, t. 24, f. 38. 
On AvicuLa (p. 261). See, likewise, Zeit. Mal. 1848, 1849, 1851, 
1852, Proc. Bost. 3, 4, and D’Orb. Cuba Shells. 
Avicula semisagitta, p. 261, t. 24, f. 39. 
On Metmaerina (p. 264). See, likewise, Zeit. Mal. 1849, 1852, 
Sw. Z. I. s. 2, t. 55, and D’Orb. Cuba Shells. 
Metracrina Mazatuantca (t. 24, f. 40). Large, solid, subven- 
tricose, more or less oblique, more or less projecting behind ven- 
trally, longer than broad, squarish above in front; rounded ventrally, 
yellowish olive, with rather faint pallid rays; the rather distant con- 
centric lamelle somewhat closely fringed with moderately large 
peaked concave vandyked scales ; ventral edge much arcuated, rising 
in front; anterior margin not retuse, but either straightish or 
convex, forming nearly a rectangle with the rather short straight 
and rising dorsal line; hinder gape ample, the posterior dorsal 
incurvation being full, and the auricle rather large and deep; nacre 
bluish white, broadly edged with the external colouring. 5...43. 
Mazatlan. Distinguished from margaritifera by its scales, obliquity, 
colour, and by not being retuse in front. 

1 Was designed by Hinds to have been published in the Zoolo- 
gical Proceedings, but his intention was not carried into execution : 
it has been subsequently termed falcatus by D’Orbigny (S. Am.). 
