104 MONOGBAPH OF THE GENUS GNATHODOK—DALL. vol. xvii. 



gin of the valves, especially near the hiuge, sometimes sliows faint 

 radiating .striation, as already noticed in G. mendicus. 



Spurious or Doubtful Sj)ecies. 



MIJLINIA GUADELUPENSIS, Recluz. 



Macira guadehqyensis, Recluz, Journ. de Concliyl., in, p. 249, pi. 10, figs. 4, 4', 

 1852; Jonrn. deConchyl., iv, p. 414, 1853.— Beau, Cat. Sh.Guad., p. 26, 1858.— 

 Krebs, W. I. Marine Sh., p. 105, 1864. 



Gnathodon (juadalKpensis, Rkkve, Conch. Icon., xix. No. 2, 1873. 



Macira douaclformis, Krebs, W. I. Mar. Shells, p. 105, 1864 ; not of Gray or Reeve. 



Gnathodon Cantrainei (Recluz ms.), Reeve., Conch. Icon., xix, Gnathodon, fig. 3, 

 Oct., 1873.— GUNDLACH, Ann. Soc. Esp. de Hist. Nat., xii, pp. 280,322, 1883. 



Beach at Aguadilla, Porto Rico, dead shells cast up on the shores of 

 the creek, Guudlach; Xevis, Sowerby; Guadelupe, Kecluz, Beau; 

 Guaivea on the coast of Venezuela, Blume in Swift Coll. 



Gray described a shell in 1837 under the name of (lonacdformis, hnt 

 his description was inadequate. It was later figured by Sowerby in 

 the zoology of the voyage of the Blossom, Capt. Beechey, and on this 

 figure the name must rest, as there is no other means of identifying the 

 shell. It represents a species found on the west coast of middle Amer- 

 ica from Panama ro the Colorado River. It is quite a variable shell 

 but normal specimens agree well with Sowerby's figure. It was stated 

 by Gray to come from the "South Seas" (then a term including most 

 of the Pacific); Sowerby gave the locality as "Xevis," an island in the 

 West Indies where Beechey did not touch ; later Reeve figured a shell, 

 l)robably young, said to be from New Zealand, under Gray's name. 

 The reference to "Nevis" led Krebs and others to identify a rather 

 similar but smaller species named (luadelupensis by Recluz with the 

 donaciformis of Sowerby and Gray. Eecluz' species Avas subsequently 

 figured by Sowerby (1873) in his continuation of Reeve's Iconica as a 

 Gnathodon, a not unnatural mistake, since these Mulinias and Fangia- 

 nella can barely be separated generically. At the same time another 

 Mulinia, probably a mere variety of guadelitpensis, is figured by Sow- 

 erby under the (ms. f) name of Cantrainei Recluz, and also referred to 

 Gnathodon. From an examination of authentic specimens there seems 

 to be no question of the identity of G. Cantrainei with G. guade- 

 lupensis, while it is absolutely certain that both belong to the genus 

 Mnlinia of Gray. 



This, however, is not the final disposition of the matter. The small 

 Mulinia, named lateralis by Say, is well known, chiefly from northern 

 specimens. It extends from Massachusetts Bay to the Antilles. The 

 northern specimens are rather rude, but a series showing the geograph- 

 ical range also shows that, as we follow the species south, it becomes 

 more delicate, lighter, and develops several varieties, one of which 

 was named Mactra rostrata by Philipjii (not of Spengler) and Mactra 

 corbuloides, by Beshayes. This rostrate form is connected with the type 

 by insensil)le gradations. Tlie species under favorable circum- 



