364 ZOOLOGY. 



OCTOPODS. 



Octopus Bairdii V. Octopus lentiis V. 



piscatorum Y. Stauroteuthis syriensis Y. 



ohesus Y. Alloposxis mollis Y. 



YEETEBRATES. 



NOIMENCLATURE OF LIMB SEGMENTS. 



lu connection witli an article on the Ichtliyosanrian Sauranouou (snb- 

 seqiiently renamed Baptanoclou),* Professor Marsh has proposed a new 

 nomenclature for "the corresponding segments alike of the anterior 

 and posterior limbs of the air breatliing vertibrates." liecallmg that 

 the terms "phalanges" and "metapodials" had already been applied 

 and obtained general currency for the distal segments, he proposed to 

 complete the nomenclature as follows : 



Anterior. Posterior. 



Propox^odial bones Humerus. Femur. 



Epipodial bones Kadius and ulna. Tibia and fibula. 



Mesopodial bones Carpals. Tarsals. 



Metapodial bones Met;icarpals. Metatarsals. 



Phalangeal bones Finger bones. Toe bones. 



THE SEMICIRCULAR CANALS OF VERTEBRATES. 



Dr. Francis Dercum has investigated the morphology of the semi- 

 circular canals in the vertebrates.t He recalls the fact that the structure 

 of the mucous canals and of the semicircular canals is very similar, as 

 Leydig, m ISoO, had already observed. Deeming this analogy complete 

 he asks, " Would it now be too hazardous to suggest that the two 

 organs which are so closely related in structure and which present 

 such significant facts as regards nerve supply and embryological devel- 

 opment, are related genetically f Such si>ecialization would not be in- 

 consistent. Let us see how it may have been brought about. In an 

 organism provided with a general apparatus for the perception of vibra- 

 tions, evidently the first thing that would take place would be the 

 specialization of certain portions for certain classes of vibrations. This 

 is what may have been the case with the lateral canals and the ear, 

 each being a specialization in its own peculiar direction. The fact that 

 the involution of the side organs in Teleosts does not take place until 

 the organism is already far advanced towards the completion of its 

 development, and the fact that the mucous canal in the embryo of 

 Elasmobranchs does not appear until the epiblast has been difierentiated 



* Marsh (O. C.)- The limbs of Sauranotlou, with notice of a new ppecii'S. Am. 

 Journ. Sc. and Arts, (3), vol. xix, pp. 169-171, Feb., 1880. 



tDercuui (Francis). On the Moii)hology of the Semicircular Canal, Am. J^at., 

 vol. xiii, pp. 366-374, June, 1879. 



