(36) 



anteversion, wliicli (|iückly decreases, so that the 4^^' and o"^'^ myo- 

 tomes are strictly vertically situated. The foilo\vin<i- myotomes (as in 

 figure II) are i-etro versed, this retroversion reaching a nia.xinunn of 

 10°. Towards the caudal end of the body this retroversion decreases 

 and is again reversed behind rhe anal aperture, where the myotomes 

 are again an reversed. 



The description given here of the myotome applies only to the 

 trunk-myotome in the middle region of the body, the brancliial 

 apparatus as well as the appearance of the dorsal fins bringing 

 about notable changes in this form. 



II. Trtdil-iniiotoine of Acanthias vuh/aris. (F'kj. TV and Y). 



The myotome described in Ihis [)aper was situated in ihal r(\ü;ioji 

 of the bodv which lies between the thoi'acic lin and the lirsl dorsal 



Fig. VI. 



tin. In its most general features the trunk myotome of Acanthias 

 shows a great resemblance with that of Petromyzon, though at first 

 view a considerable difference seems to exist. 



Looking at that surface of the myotome, which forms part of the 

 surface of the body, we see it interrupted in two places. 



The lines of iutei-ru[)tion are nearly parallel to the sagittal axis 

 of the trunk. The first line {LL fig. VI) coincides with the linea 

 lateralis, the second {L'lJ tig. VI) lies nearer the mid-ventral line 



