SEA-FISHERIES LABORATORY. 833 



On its anterior face the endosternite is connected 

 with the narrow plate-like second thoracic endopleurite 

 (/.). Near the point of junction of these two plates the 

 dorsal and articular borders are prolonged backwards as 

 rod-shaped pieces, each of which comes into contact with 

 anterior rod-like outgrowths from the corresponding 

 borders of the third thoracic endopleurite. 



The endopleurite arises betwen the third and fourth 

 epimera. It gives off two short anterior rod-like 

 prolongations from the dorsal and articular borders which 

 fuse with the rod-like extensions of the endosternite 

 mentioned above. The main part of the endopleurite, 

 however, consists of a broad plate, which passes backwards 

 and fuses with the fourth thoracic arthrophragm (e.). 



Second thoracic arthrophragm (Text fig. 7, IK). 

 The endosternite is much more reduced than that of the 

 third thoracic arthrophragm. It arises from the 

 upturned edge of the sternum in this somite, and has a 

 very irregular shape. Its inner portion passes upwards, 

 and fuses with a narrow membranous process projecting 

 downwards from the last cephalic endopleurite {!>.). 



The articular border is prolonged outwards as a rod- 

 like process, which fuses with the extremely small 

 articular border of the endopleurite of the same arthro- 

 phragm. About half way along the articular border the 

 endosternite fuses with a posterior rod-like extension of 

 the first thoracic endopleurite (7/.). 



The endopleurite of this arthrophragm is a deep 

 narrow plate arising at the junction of the second and 

 third thoracic epimera. From its lower end it sends 

 forward a short process which fuses with the outer part of 

 the endosternite. The main part of the endopleurite 

 passes backwards and becomes fused with the third 

 thoracic endosternite (C), as described above. 



