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PROCEEDINGS OP SOCIETIES. 
this crustacean, in which he had been interesting himself in study 
recently, and alluded to the probable development in the way of 
organs of seeing, smelling, and especially hearing. The eyes were, 
no doubt, once but simple feelers, and by a process of evolution had 
developed into appendages. The organs of smelling were the larger 
of the remaining pair of feelers — antenna — while those of hearing 
were located in the smaller pair, or antennules. The parts of the 
latter were easily dissected out with a pair of scissors, and the 
lobster’s car, in the shape of an auditory sac, handed about on a 
needle for examination. Placing a prepared fragment immersed in 
glycerine, on a slide, the sensitory hairs were beautifully shown, 
standing out from a telephonic floor, so to speak ; and the previous 
explanations, by means of diagrams on the black-board, were rendered 
still more plain, and the method in which the little hairs would 
receive sensations from vibrations in the fluid in the sac made 
theoretically clear. Mr. Clark also exhibited several slides showing 
colonies of bryozoans and beautiful little calcareous helices of serpula, 
on some fronds of a fucus. 
Dr. Gustav Eisen, Professor of Zoology, Upsala, Sweden, a 
corresponding member, called attention to some minute worms of the 
Oligochasta, of the family Tabificidce, and exhibited some fine plates of 
beautiful drawings made by his skilful hand, representing their 
anatomy. The worms were all found in California, near San Fran- 
cisco, in the Sierra Nevadas, or in the red-wood forests along the 
northern coast, all inhabiting ponds, lakes, or even clear running 
streams. Of said family, only five genera are known, viz. : Tabifes, 
Psamoryclites, Phrcatotrix, Limnodrilus, and Thelmatodrilus. Of 
those, all except Phrcatotrix were found in California, and one, the 
Thelmatodrilus, was endemic to the waters of the higher Sierra 
Nevada. The Doctor called attention to some points in their 
anatomy, and pointed out some characters by which species and 
genera could easily be distinguished, as in the Oligochaeta generally 
no external characters are found, and the species must be arranged 
according to the shape of their interior organs. As a generic 
characteristic, the supracesophageal ganglion is of great value, but as 
to specific characters the generative organs were undoubtedly the best. 
The organs represented on the drawings were principally the nervous 
system, the ovaries, the testes, the efferent ducts and the segmental 
organs, all exhibiting characteristic forms in the different species. 
The species described were Limnodrilus crinis medusae, Limnodrilus 
vejdoorleyi, Limnodrilus corallinus, Tabifes mirabilis, Thelmatodrilus 
alpestris and Psamoryetes Californicas. Besides these, many new 
forms had lately been found, hut many more yet were likely to occur 
in our stagnant ponds or rivers. The Doctor expressed his hope that 
the members of the Society, during their excursions, would capture 
and preserve all such worms found, and any contributions, however 
small, should be most thankfully appreciated. Nearly every large 
body of water contains one or several new forms, and a perfect 
collection could only be brought up by a diligent search in different 
parts of the country. 
