6 MR. E. J. SIDEBOTHAM ON THE [Jan. 20, 



diverticula of the annular stomach ; e, annular etoinach ; S, suctorial 

 organ ; in, nerves of the fourth pair of ambulatory legs ; n, abdominal 

 nerve. 

 Fig. 2. Diagram of the left part of the eephalothorax of Mygale cxmentaria, 

 Latr., to show the horizontal projection of the coxal gland ; X64-. 

 a, The coxal gland. 1, Cheliferre. 2, Chelas. 3-6, The four last 

 pairs of cephalothoraeic appendages. A. Abdomen. 



3. The same specimen as in fig. 4. To the left hand the upper prolon- 



gations {p) of the entosternite show only the coxal lobes (a) of the 

 gland ; on the right, the same prolongations and the lateral diver- 

 ticula {d) of the aniuilar stomach hide all but very small parts («) of 

 the gland. 8. Suctorial organ. 



4. The left coxal gland and the entosternite of Mygalc, sp.. from South 



America, in situ, dorsal view; y.'!^. The superior prolongations of 

 the etitosternite have been removed along the line ii, to show, on 

 the right side, the coxal gland in its entirety, and on the right side the 

 lower plate of the entosternite, which on the left is hidden by the 

 gland, a, The coxal gland ; h, its coxal lobes ; c, its internal projec- 

 tions. E, The entosternite. 3-6, The coxis of the ambulatory legs. 

 A.B, Line showing the direction of the section in fig. 1. 



2. On the Myology of the Water-Opossum. By E. J. 

 SiDEBOTHAM, B.A.j late Assistant Demonstrator of 

 Anatomy, Cambridge. 



[Received November 20, 1884.] 



Through the great kindness of Professor MacaHster I have had 

 the opportunity of making a careful dissection of the muscular 

 system of the Water-Opossum {Ghironectes variegatus). 



The specimen, which was that of a young male, was a spirit one, 

 and the muscles were in a very good state of pieservation. 



When I received it the skin and abdominal viscera had been 

 removed, some of the superficial muscles were considerably damaged, 

 and most of the terminal phalanges had disappeared. 

 It had the following dimensions : — 



centim. 



Extreme length 5'J 



Length of tail (measured from sacro-iliac synchondrosis). . 37'4 



Length of humerus 4-1 



Length of femur 5 



Length of tarsus (terminal phalanx having disappeared) .. 6"1 



Through the courtesy of Professor Flower I was enabled to 

 measure the five specimens of this animal in the National Collection 

 at South Kensington. 



The four stuffed specimens varied in length from 68'7 cm. to 

 41'5 cm., the tarsus varying from 6'7 cm. to 3'9 cm. 



The skin of the remaining specimen measured 67'6 cm, in length, 

 the femur 5*6 cm., the humerus 4/ cm., and the tarsus 5'9 cm. 



Muscles of Anterior Extremity. 



Rhomboideus. — Indivisible, arising from inner two thirds of 

 occipital crest, from spines of cervical and first five dorsal vertebrae. 



