340 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



of the unequal functions of the two organs, appeared to be the rule, as 

 is the case with many hermaphrodite flowers from the same causes. 



Some fishes are only occasionally hermaphroditic, that is to say, 

 among distinctly bisexual fishes hermaphrodites g,re occasionally ob- 

 served. Among these belong the mackerel and the carp. 



CONTRIBUTIONS TO THE HISTORY OF THE COMMANDER ISLANDS. 



NO. :t Ri:i>ORT ON THE ITIOI.I.IHCA OF THE t'Oin.^IA.\I>EK l!^l» 



AIVI>!!i, llt:Hl?tU HE A, I'OLEECTED BV I.EOIVHAKI> HTEJNECIEK IIV 

 188.2 ANI> 1883: BV W. H. DAEE. 



I am informed by Dr. Stejneger that the coast of the Commander 

 Islands, especially Bering Island, is largely rocky, comiyOsed chiefly of 

 sandstone, which extends in rocky flats from the shore at the base level 

 of erosion by the waves for quite a distance seaward ; from small capes 

 or projections a reef invariably extends seaward, often of volcanic rock. 

 The shore is thus composed of a succession of small bays or bights, 

 none of which aflbrd a harbor, and only one or two an anchorage even 

 for small craft. The beaches at the head of these bays are rocky, or 

 composed of shingle with an occasional strip of sand, the latter espe- 

 cially where streams fall into the sea. There are several lakes at the 

 northern part of Bering Island ; the soil is covered with that moss-like 

 coating of sphagnum, reindeer lichen, and Empetrum which is charac- 

 teristic of those regions, with an admixture of the usual boreal herbage, 

 dwarf willows, Yaccinium^ sedges, and grasses. 



These features, taken ru connection with the geological character of 

 the rocks, are not favorable to a profuse development of molluscau life 

 of any description. 



Upon the wave-worn rocks the stony alga, Melobesia, forms crusts, 

 which, by the superposition of successive thin layers, forms masses 

 sometimes 5 or G inches thick. In this the boring bivalves find a har- 

 bor and congenial quarters. The ponds and lakes aflbrd two Hmnceas 

 and a small Pisidium. 



The little black northern slug, Limax hyperhoreus^ is found under 

 protecting chips or pieces of drift-wood near the shore. A few minute 

 helices are its companions. A more exhaustive search would perhaps 

 enlarge the list of Pulmonates, but the usually common and conspicu- 

 ous genus Succinea is singularly absent and hardly likely to have been 

 overlooked. It is quite possible that some of the land shells have been 

 introduced from Kamchatka; the presence of Patida fioccula is perhaps 

 explainable on this hypothesis, which w^ould account for its absence 

 from the Aleutian Islands. 



It is not probable that the Commander Islands have been connected 

 with the mainland of Asia or with any of the Aleutians within recent 

 geological time. The depth of water and the distance which separate 



