ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 353 



nervous terminations ; they are nothing more than mere fibres of con- 

 nective tissue, which have no connection with the chromatophore. 

 Henceforward the chromatophores of the Cephalopoda will not be 

 allowed to form an exception to the general rule that muscular fibres 

 never become inserted into cells, connective or other, and the whole 

 phenomena of their change in coloration will be brought into asso- 

 ciation with what is seen in other forms. 



Deep-Sea Solenoconcha.* — P. Fischer points out that the mollus- 

 can fauna of great depths is characterized by the great abundance of 

 individuals, but the small number of genera and families ; among the 

 Mollusca best represented are the Solenoconcha or Scaphopoda, opis- 

 thobranch and prosobranch Gasteropoda and Lamellibranchs. The 

 first of these seem to be well adapted for living in the bottom of the 

 ocean ; ordinarily without eyes, they capture by the aid of their 

 tentacular filaments the surrounding Foraminifera ; they would seem 

 to be present in great numbers, and the best represented species is the 

 Dentalium agile, described by Sars from dredgings in the Northern 

 Seas. A gigantic specimen, dredged by the ' Travailleur,' and now 

 named D. ergasticum, was, when alive, more than 9 cm. long, and its 

 shell is very thick and solid ; another, which was probably still 

 larger, cannot be specifically distinguished from an Italian pliocene 

 fossil, and other cases of the same kind lead to the belief that many 

 pliocene fossils supposed to be extinct still live at the bottom of the 

 Mediterranean. Indeed the pliocene Mediterranean must have had a 

 contour and fauna very little different from that of to-day, though 

 there must have been a great difference in the Southern European sea 

 of the miocene period. 



Vascular System of Naiadse and Mytilidse-t — In this essay H. 

 Griesbach considers the vascular system and the ingestion of water in 

 some Lamellibranchs. He finds that the peripheral tracts of the 

 vascular system are not closed, but that between the arterial and 

 venous portions there are intercalated spaces without walls or endo- 

 thelium — that is, lacuna in the gelatinous tissue. True capillaries 

 are never found, except in the gills of a few forms, among Lamelli- 

 branchs. The venous portion of the vascular system is complete, and 

 represents the remainder of the coelom, while the lacunae are ccelom 

 par excellence. The so-called vesicles of Langer, or mucous cells 

 of Flemming, do not exist as such, but are the true lacunae. In the 

 interior, as at the periphery, the vascular system is not closed, but 

 it there communicates with the surrounding medium. The fluid 

 circulated in the vascular system is a mixture of haemal constituents 

 and water. The water enters by the pori aquiferi, and passes out 

 through the organ of Bojanus. There is no special water-vascular 

 system, but the ingestion is a constant phenomenon. 



After pointing out the present condition of the question, the 

 author gives a detailed account of the work of his predecessors, and 

 then proceeds to adduce facts in favour of the above-mentioned con- 



* Oomptes Eendus. xcvi. (1883) pp. 797-9. 

 t Zeitschr. f. Wiss.' Zool.,xxxviii. (1883) pp. 1-44 (1 pi.). 

 Ser, 2.— Vol. III. 2 A 



