67 



igoç- Mytiliis [Hormomya] variabilis Lamy, Mém. Soc. Zool. France, XXII, p. 337. 



1910. Mytiliis variabilis Dautzenberg, Journ. Conchyliol., LVIII, p. 30. 



1919. Mytilus [Hormomya) variabilis Lamy, Bull. Mus, d'Hist. Nat. Paris, XXV, p. 42. 



1926. Mytilus Hormomya variabilis Pallary, Mém. Inst. Egypt., XI, p. 116, pi. XV, fig. 5. 



1927. Brachidontes variabilis Tomlin, Trans. Zool. Soc. London, XXII, p. 302. 



1929. Mytilus [Hormomya) variabilis Dautzenberg, Faun. Colon. Français., III, Fasc. 4, p. 570. 



Various authors such as Dunker ^), Cooke (loc. cit.), Smith") and Dautzenberg'') hâve 

 at différent times included this species in the synonymy of the American species B. {H.) extishts 

 (Lam.) or the West African B . {H.) senegalensis (Lam.). I, however, am of opinion that Krauss's 

 species B. {H), variabilis is quite distinct from either of thèse species and is confined to the 

 Indo-Pacific région and the Red Sea only. This appears to be the idea of Monsieur P. Dautzenberg 

 as well, for in his récent work on the Molluscs of Madagascar (1929) he considers B. {H.) variabilis 

 as a distinct species. 



As Tomlin has recently shown the species belongs to Swainson's genus Brachidontes^ 

 and adopting Jukes-Brown's nomenclature it has to be placed in the subgenus Hormomya Morch. 



Distribution: — Tomlin remarked that the species "has probably alvvays been a widely- 

 distributed species throughout the E. coast of Africa", and is very common in the Suez Canal 

 and the Red Sea, while Melvill and Standen had recorded it from the Mekran Coast and 

 Karachi. Smith had also recorded the species from Port Alfred and the Island of Rodriguez. 



In the "Siboga" collection there is a single shell collected on a reef near the Fau 

 Anchorage, West Coast of Gebe Island (St. 149), which I am unable to separate from spécimens 

 of B . {H.) variabilis from the Red Sea. 



2. Brachidontes [Hormomya) sztbramosus (Hanley). 



1843. Modiola subramosa Hanley, Rec. Biv. Shells, p. 241, pi. XXIV, fig. 30. 



1844. Modiola subramosa Hanley, Proc. Zool. Soc. London, p. 14. 



1845. Modiola subramosa Catlovv & Reeve, Conch. Nomencl., p. j^i- 



•1857. Modiola subramosa Reeve, Conch. Icon., X, Modiola, pi. VIII, fig. 43. 

 1857. Perna [Brachyodontes) subramosa Adams," H. & A., Gen. Rec. MolL, II, p. 517. 

 1860. Modiola subramosa Reeve, Elem. Conch., II, p. 172. 



1887 — 89. Modiola subramosa and M. ramosa Clessin in Martini & Chemn. Conch. -Cab. (N.F.) 

 VIII (3) Mytilidae, p. 121, pi. XXXI, fig. 11 ; p. 134, pi. XXVI, fig. 8. 



1890. Modiola ramosa and M. [B.) subramosa Paetel, Cat. Conch. Samm., III, pp. 197, 198. 



1891. Modiola subramosa Bottger, Ber. Senckenberg. Nat. Ges., p. 310. 



1896. Modiola [Brachiodontes) subramosa Casto de Elera, Cat. Sist. Filip., p. 794. 



1897. Modiola [Brachy doutes) subramosa von Martens in Weber's Zool. Ergebn. in Niederl. 



Ost.-Ind., Sùss.-Brackw. MolL, IV, p. 226. 

 1905. Modiola subramosa Hidalgo, Cat. Filip., p. 364. 

 1905. Brachyodontes [Hormomya) subramosa Lynge, D. Kgl. Dansk. Vidensk. Selsk. Skr. Nat.- 



Math., (7) V, p. 134. 

 1911. Modiola subramosa Pelseneer, "Siboga" Lamellibranches (Anat.) p. 17, pi. V, figs, 3, 4. 

 1930. Brachydontes [Hormomya) subramosus Thiele, Faun. Siidwest Austral., V, p. 590. 



I agrée with Lynge that Clessin's Modiola ramosa is based only on a slightly distorted 

 shell of B. {H.) szibramosus. 



i) DUNKER, W. — Ind. Moll. Guinea CoU. Taras, p. 47 (1853). 



2) Smith, E. A. — Proc. Zool. Soc. London, p. 430 (1891). 



3) Dautzenberg, P. — Mém. Soc. Zool. France, IV, p. 55 (1891). 



