NOTES ON THE ANATOMY OF NAUTILUS 



POMPILIUS. 



LAWRENCE E. GRIFFIN, B.A., B.Pn. 



SCHOLAR IN THE DEPARTMENT OF ANIMAL BIOLOGY OF THE UNIVERSITY OF MINNESOTA. 



[The valuable material upon which these notes are based was presented to the 

 Department of Animal Biology of the University of Minnesota by Mr. Louis 

 Menage, and I am indebted to Professor Nachtrieb for placing it at my disposal, 

 and for the aid he has given me during the progress of the work.] 



ATTACHMENTS OF THE MANTLE TO THE SHELL. 



THE body of the Nautilus is held within its shell mainly by 

 means of two large shell-muscles, which are attached to the 

 shell at each side over large crescentic areas, nearer the dorsal 

 than the ventral side of the animal. Between the ends of the 

 muscles and the shell are thin plates of a chitinous substance 

 which are sometimes spoken of as tendons. These tendons 

 are light brown, and are composed of a large number of very 

 thin layers. The long axis of the muscle attachment is 

 directed dorso-ventrally. 



The mantle also is attached to the shell along three separate 

 lines, which extend between corresponding points of the shell- 

 muscles. Huxley ('58) named these " aponeurotic bands." 

 This general name I have found it convenient to retain, while 

 naming each separate band according to its position as follows : 



The dorsal aponeurotic band, extending between the dorsal 

 ends of the shell-muscles over the dorsal surface of the body. 



The anterior ventral aponeurotic band, extending between 

 the ventral ends of the shell-muscles around the ventral sur- 

 face of the body. 



The posterior ventral aponeurotic band, extending between 

 the dorsal ends of the shell-muscles around the ventral surface 

 of the body, posterior to the anterior ventral band. Owen 

 ('32) described the two first-mentioned bands, the dorsal and 

 anterior ventral, and other writers have since noted them. 

 Of the third band, the posterior ventral, I find no mention in 

 any of the literature on the subject. Thin bands of the mate- 



