von jeering: on south American MViiLiDiE. 91 



This is a Brazilian species, occurring from Bio de Janeiro to 

 -St. Catharina ; the shell, sometimes elongate, sometimes triangular, 

 'always shows the following characteristics. The zigzag marks, 

 ^developed or absent, as in If. lotus, etc. The largest specimens are 

 80-90 mm. long, while the examples of If. elongatus, of 130-140 mm., 

 figured by Clessin (Conch. -Cab., pi. iii, fig. 1), refer to II. latus. 

 The shell is thin. The If. perna from South Africa is a more solid 

 shell, with porcellaneous nacre, perhaps only a variety of If. afer, Cm., 

 or If. pictus, Born, which is a larger and more triangular form. 

 M. latus, Dillw., from New Zealand, is a very closely allied species, 

 of which If. smaragdinus, Chein., is a variety. 



. On the eastern coasts of South America we have only one species 

 belonging to the Chloromya group, which I hold to be distinct from 

 the M. perna of South Africa. 



On the South African coast the Chloromya section is represented by 

 M. chorus, Molin. (= If. meridionalis, Krauss, If. ungulatus, Rve.), 

 M. perna, Linn., If. pictus, Born. The last-named occurs also at 

 Algiers, Guinea, etc., and I do not believe Clessin's statement that 

 M. smaragdinus, Chem. (an Indian Ocean species), occurs on the Guinea 

 coast, to be correct. The New Zealand representative of this subgenus 

 is If latus, Dillw. (=11. cuneiformis, Rve. ?), a point which must be 

 verified, in the event of the species occurring also on the Chilian coast. 

 The synonymy of If. perna, If. elongatus, etc., which depends upon the 

 habitat of the respective types, should likewise be investigated. 



Subgen. AULACOMYA. 



5. Mytilus Magellanicus, Chem. 



Ifytilus Magellanicus, Chemnitz : Conch. -Cab., vol. viii (1785), p. 162, 



pi. lxxxiii, figs. 742-3. 

 ,, ,, Chem. : Reeve, Conch. Icon., vol. x (1858), 



sp. 22. 

 ,, ,, Chem. : Orbigny, Voy. Arner. merid., torn, v 



[1846], p. 647. 

 ,, ,, Chem. : Clessin, Conch. -Cab., 2nd ed., p. 54 



(1887), pi. iii, figs. 8, 9; pi. vii, fig. 7. 

 ,, „ Chem. : Martens, Jahrb. Deutsch. Malak. Ges., 



Bd. i (1874), p. 124. 

 ,, ,, Chem. : Martens, Mai. Blatt. (1872), p. 8. 



,, ,, Chem. : E. A. Smith, Phil. Trans., vol. clxviii 



(1879), p 188. 

 ,, ,, Chem. : Tapparone-Canefri, Zool. Viag. Magenta, 



: Malac. (1874), p. 140, or Mem. Accad. Sci. 



Torino, ser. n, torn, xxviii (1876), p. 244. 



This large, well-known species occurs on the eastern side of 

 ' Patagonia to the Rio Negro, and on the western, according to Philippi, 



to Caldera; the species also occurs in Southern Africa, New Zealand, 

 i and at the Fiji, Auckland, Campbell and Kerguelen Islands. On the 



northern shores of Chili and on the Peruvian coast, it is replaced by 



