Dr. Strahl on a Species of Riippellia. 299 
Enida, which I have recently discovered, and in the species 
Eburna japonica and Haliotis japonica. 
The remainder, or possibly the greater part, of the Molluscan 
inhabitants have been introduced by foreign immigrations from 
the north, south, and west. 
1. Boreal or Northern Forms. 
These have travelled from the Sea of Okhotsk, passing through 
the Strait of La Pérouse, and, following the prevailing cold current, 
according to our observations, have distributed themselves along 
the coast of Manchuria and the shores of Yesso. Some of these, 
for example Cryptochiton Stellert and Littorina grandis, may 
have been derived from the Shantar Sea, having passed through 
the Gulf of Amur into the Gulf of Tartary. 
2. Indo-Chinese or Southern Forms. 
These, issuing from the China, Eastern, and Yellow Seas, have 
entered by the Korea Strait, and, following the prevailing warm 
current along the shores of Niphon, have spread themselves 
over the Sea of Japan, mingling with species from the north 
and west. 
3. Pacific or Western Forms. 
These mollusks have crossed the North Pacific Ocean,. and 
passed into the Sea of Japan by the Straits of Tsuka and La 
Pérouse. Among them may be instanced Saxidomus Nuttalh 
and Gemma gemma. Saghaleen has derived some species from 
Sitka, the Manchurian coast from Oregon, and the islands of 
Yesso and Niphon from California. 
I can say nothing from personal observation concerning the 
influence of the gulf stream of the North Pacific, but possibly 
during the summer of the present year 1 may have an opportunity 
of visiting the western coast of Niphon. 
Shanghai, China, May 15, 1861. 
“XXXIV.— On a Species of Riippellia, Milne-Edwards, and the 
Limits of the Brachyura. By Dr. Stran*, 
Dana, in his work on the Crustacea, describes a Riippellia which 
he identifies, with doubt, with R. annulipes, M.-E. The figure 
given by him facilitates a comparison with the statements of 
Milne-Edwards. Dana’s Riippellia is evidently a new species, 
and not to be identified with any one of Milne-Edwards’s three 
species.. The species described as Riippellia annulipes by Dana 
’ * Translated from the Monatsbericht der Konigl. Akad. der Wiss. zu 
Berlin, November 1861, p. 1004. 
