212 



DR. A. A. W. HUBRECHT. 



A Contribution to the Morphology of the Amphineura. By 

 Dr. A. A. W. HuBRECHT, Leyden. 



In August, 1881 J I was invited by the editor of this Journal 

 to furnish him with a few diagrams concerning the anatomy of 

 the Amphineura, and with a short explanatory text indicating 

 the actual state of our knowledge about this class of animals. 

 Different engagements have obliged me to postpone the fulfil- 

 ment of this wish till now. I am not sorry for this delay, now 

 that it enables me to mention the latest researches upon Chiton, 

 by Mr. A. Sedgwick, which have thrown a welcome light on the 

 difficult subject of the renal organs of the class. 



I will limit myself to a very brief statement of what appears 

 to me to be known, surmised, uncertain, or unknown with re- 

 spect to the following heads : — a, integument ; h, nervous system ; 

 c, intestine ; d, circulatory and respiratory apparatus ; e, reproduc- 

 tive and excretory organs. As it is not my intention to enter 

 into a full discussion of the different views of the several authors 

 and their respective merits, I will merely summarise those state- 

 ment which appear to me to be the most worthy of credit. A 

 list of the different authors, to which reference is made in the 

 text by means of a different number prefixed to each of them, 

 will, however, be given at the end of this paper. 



A. Classification. — The systematic arrangement of the Am- 

 phineura and the names adopted for the subdivisions are the 

 following : 



Mollusca. 



Class.'' 



Amphineura . 



Order. 

 Solenogastres 



Family. 

 rCbsetodermata 



■ 



Neomenise 



Chitoues 



Genus. 

 Chsetoderma. 

 f Neomenia. 

 X Proneomenia. 

 /'Chitonellus. 

 3 Chiton. 

 1 Cryptochiton. 

 C &c. 



V. Jhering (8) originally regarded the Amphineura as a sepa- 

 rate phylum of the Vermes ; Spengel (20) afterwards clearly 

 showed that they will henceforth have to be regarded as a class 

 of Molluscs. Chatoderma and Neomenia were linked together 

 by Gegenbaur under the name of Solenogastres, which is better 

 chosen than v. Jhering's designation of Aplacophora ; the latter, 

 moreover, ranks as a class with v. Jhering. The families of 



