760 PROF. G. C. BOURXE OX THE 



in his class Orthoneura, order Rostrifera, sub-order Rhipidoglossa, 

 and gave a fairly accurate description, unaccompanied by a figure, 

 of the nervous system of Helicina [Sturanya Wagner) beryllina 

 Gld. E. L. Bouvier (3), in his gi'eat work on the nervous system 

 of Prosobranch Gastropods, gave a ver}^ complete account of the 

 nervous system of H. sagraiana d'Orb. and H. hrchsiliensis Gray, 

 laying stress on its close resemblance to the nervous system of the 

 Neritidje, and in addition he made some further observations on 

 the general anatomy, partly confirming and paitly correcting and 

 adding to Isenki-ahe's descriptions. In 1902 Thiele (9) described 

 the male generative organs of Helicina jajwnica, and last year 

 he gave a description with a diagram of the female organs of 

 a. kubaryi, in addition to a succinct but sufiiciently exhaustive 

 account of the general anatomy of Hydrocena cattaroensis . 



The geographical distribution of the Helicinidje, as is well 

 known, presents several interesting and diflicult problems. By 

 far the greater number of species are insular and confined to the 

 tropics. Such species as are foiuid on continents are for the 

 most part limited to regions near the coast, very few being known 

 to occur any considerable distance inland, i^o Helicinidse are 

 recorded from Africa. In Europe the gioup is i-epresented only 

 by the genus Hydrocena from the Dalmatian coast, and this genus, 

 as Thiele's recent work has sho\^Ti, diftei-s in several important 

 anatomical characters from Helicina and its more closely allied 

 genera. Georissa, a subgenus of Proserpina, is the only represen- 

 tative of the gi'oup in India, and no Helicinidje have as yet been 

 recorded from Ceylon, The number of genera and species reaches 

 its maximum in the Antilles. The genus Helicina, as restricted 

 by Wagner, is fairly abundant in Mexico and the Central 

 American republics, and extends northwards into Texas and 

 Florida, southwards into Ecuador and Peru on the west coast and 

 to the south of Brazil on the east coast of S. America. Few 

 species, however, are recorded from the Pacific coast of S.America, 

 but, notwithstanding their comparative rarity on these shores, 

 the group reappears in great abundance in the Pacific islands, 

 extending as far east as the Marquesas and Paumotu Islands, and 

 having many representatives in the Society, Samoan, Friendly 

 and Fiji Islands, and in the JSTew Hebrides and New Caledonia. 

 Several species occur on the east coast of Australia, and some 

 few are recorded from New Guinea, Celebes, Borneo, and Sumatra ; 

 none, so far as I can ascertain , from Java. But in this part of 

 the world the Helicinidae attain their maximum in the Philippine 

 Islands, which are only second to the Antilles in the number of 

 species. From thence the group extends north, beyond the 

 tropical zone, to the Bonin Islands and Japan. A few species 

 are found beyond the south-east coast of China and Siam, others 

 again in the Malay Peninsula and Bm-ma. Several species are 

 found in the Andaman and Xicobar Islands, but the group is 

 very poorly represented in the Indian Ocean. Aphanocojiia 

 (Helicina) theohakliana G. & H. Xevill is recorded from the 



