JCJKES-BKOWNE : DOSISIA AND ITS SUBDIVISIONS. 103 



is a strong 4th cardinal, and the posterior margin is grooved. The 

 pallial sinus is short and nearly horizontal, sometimes rounded and 

 sometimes angular. 



Phacosoma (Jukes-Browne). — This has been defined on p. 100; it is 

 distinguished from Austrodosinia by the broad well-marked escutcheon 

 and by the oblique median tootli of the left valve, between which and 

 the anterior there is a wide triangular space. The pallial sinus is 

 also deeper and is always angular. 



Feetunculus (Da Costa). — Lunule moderately impressed. No 

 escutcheon. In the L.V. a small anterior lateral near the anterior 

 cardinal ; the middle cardinal broad and obscurely bifid, the front 

 part being united to the anterior tooth. In the R.V. the 4th cardinal 

 is weak or obsolete ; the posterior margin has a shallow groove Avhich 

 is often obsolete in adult shells. Pallial sinus deep, rounded or 

 obtusely angular, and generally ascending. 



Bosinidia (Dall). — Lunule very little impressed. No escutcheon. 

 In the L.V. a small pustular anterior lateral close to anterior cardinal, 

 middle cardinal broadly bifid and united to anterior tooth ; posterior 

 cardinal thin and weak. In the K.V. the 4th cardinal is distinct and 

 sharp, the 3rd is deeply bifid and has an anterior expansion over the 

 median; the marginal groove is absent (except in DunJceri and Anna) . 

 Pallial sinus fairly deep, ascending, and angular. 



Sinodia (Jukes-Browne). — This has been sufficiently defined on 

 p. 100. 



Cordiopsis (Cossmann). — Shell orbicular, thick, generally tumid, 

 with incurved umbones and cordiform frontal aspect. Lunule super- 

 ficial. No escutcheon. In the left valve a small pustular anterior 

 lateral which becomes obsolete with age ; middle cardinal thick, 

 central, rugose, and united at the top to anterior tooth. In R.V. 

 there is no 4th cardinal, but the posterior margin is grooved. Pallial 

 sinus very short, small, and rounded. 



In conclusion, a few words about the geographical distribution of 

 the recent species may be useful. Those of the typical section are 

 restricted to the old world, ranging round the shores of Europe, 

 Africa, and Asia, the most eastern species being D. prostrata and 

 L. exasperata, which occur in the Philippine Islands and in North 

 Australia. The species of Dosinella have a restricted distribution, 

 dilecta coming from Malacca and Siam, angulosa from the East Indian 

 Islands, Malacca, and the Philippines, penicillata is Australian, and 

 Bruguieri ranges from Australia to Japan. Austrodosinia is also an 

 eastern ocean group, the species ranging from the east coast of Africa 

 to Australia, New Zealand, the Philippines, and Japan. 



The Phacosoma section is essentially Japanese, no fewer than five 

 species occurring in Japanese waters, but lamellata is Australian, 

 while puhescens and Roemeri are East African. 



The Pechmculus section is distributed round the whole of Europe 

 and Africa, but I cannot find that any occur on Asiatic coasts. There 

 are, however, a number of species in Australian waters, viz. amphi- 

 desmoides, grata, sculpta, nobilis, and incisa. 



The Bosinidia section is essentially American, occurring on both 



