8 ARKIV FÖR ZOOLOGI. BAND 8. NIO 18. 



distinct muscle. The metameric structure is traceable but 

 indistinct. The anterior part of this muscle-portion has dis- 

 appeared. The fibres ha ve a direction parallel to the lateral 

 line. The muscles of the both sides are separated from each 

 other by the enlarged profound muscles of the dorsal fin 

 except cranially where they are attached to a small area of 

 the vertebral column. The rest of the dorsal muscles show 

 distinct myomers. The myocommas have the form of a V 

 with the apex pointing cranially. The fibres are almost 

 parallel to the lateral line. When compared with the hori- 

 zontal plan, the direction of the fibres is dorsal-cranial. 

 Judging from the form of the myocommas I think this part 

 of the dorsal muscles correspoiids to the portions b and c of 

 Maurer's diagram. They act together as one muscle. These 

 muscles are quite separated from the vertebral column by 

 the muscles of the dorsal fin. Functionally the dorsal muscles 

 are di vid ed into two, one inferior formed by the portion a 

 and one superior formed by the portions b and c. These 

 two muscles are well separated from each other. Behind 

 the dorsal fin there is a pair of supracarinal muscles. 



The ventral body-muscles are partly reduced. They form 

 a muscle of a pyramidieai shape. On the lateral side two 

 different directions of the fibres can easily be seen. In the 

 superior part the fibres run from a point caudally-ventrally 

 to a point cranially-dorsally, in the inferior part the direc- 

 tion is quite the contrary. I think it is evident that these 

 different directions of the fibres represent m. obliquus supe- 

 rior, resp. m. obliquus inferior. The anterio-superior part of 

 the ventral body muscles has disappeared. Here the body- 

 wall is not provided with any muscles at all. The lower 

 part of the body contains muscles which form a continuation 

 of m. obliquus inferior. When viewed from below, the fibres 

 have two directions. Some run towards the median some 

 towards the lateral side, all diverging from one line. No 

 rectus is developed. The muscle of the both sides are dis- 

 tinctly separated in the median ventral line. Behind the 

 anal fin infracarinal muscles are developed. 



The super ficial muscles of the dorsal and anal fins have 

 perfectly disappeared. The profound muscles of these fins 

 are, on the contrary, very well developed (Fig. 9). Those 

 of the dorsal fin are attached to the whole vertebral column 



