Physiology o/'Hsematopinus tenuirostris, Barm. 105 



the hinder margin of the first segment near the dorsal muscles 

 towards the ventral side, and run thence obliquely downwards 

 towards the ventral surface to about the middle of the hinder 

 lateral margin of the second segment. Opposite to their ter- 

 minations originate the lateral longitudinal muscles of the 

 third segment, which, like those of the other segments, run 

 more parallel to the median line of the whole animal. While 

 the muscles of the dorsal and ventral surfaces by their con- 

 traction effect the contraction of the dorsal and ventral integu- 

 ments, the lateral longitudinal muscles serve for the contrac- 

 tion of the lateral integument. 



Respiratory Muscles. — In opposition to the muscles of the 

 first group just described, these traverse the abdomen trans- 

 versely. They consist of from one to three fasciculi in the 

 respective segments. The first is situated in the middle of 

 the sides of the second segment. It originates near the lateral 

 muscles of this segment and runs towards the ventral surface. 

 In the third segment the respiratory muscle is inserted near 

 the dorsal muscles towards the ventral side, stretches over the 

 lateral longitudinal muscles, and terminates between the latter 

 and the ventral muscles. We also find a muscle of this kind, 

 which, however, is considerably smaller, in the middle of the 

 fifth segment. The other respiratory muscles are situated on 

 the boundaries of segments three to eight. They all originate 

 on both sides of the dorsal, muscles, and pass over the lateral 

 longitudinal muscles into the neighbourhood of the ventral 

 muscles. The action of these muscles will be noticed here- 

 after. 



Muscles of the Generative Organs. — In the female sexual 

 organs the muscular apparatus is as follows. As already 

 stated, the vagina is surrounded by a number of circular (c) 

 and longitudinal (I) muscular fibres. From the seventh seg- 

 ment come two muscular fasciculi, which, running obliquely 

 downwards, traverse the eighth abdominal segment, and at- 

 tach themselves to the vagina in the upper part of the ninth 

 segment. They are long muscular fasciculi, consisting of a 

 great number of fibrillar. (They may be called aa.) On the 

 anterior lateral margins of the ninth segment two shorter and 

 thinner fasciculi are inserted, which stretch somewhat upwards 

 and attach themselves to the vagina a little before the first 

 mentioned (bb). At the bottom of the last segment we see on 

 each side a powerful but short muscular bundle, which runs 

 from the sides towards the genital cleft, and has for its office 

 to dilate the latter (cc) . All these muscles are of great im- 

 portance in the act of parturition. When the egg has got 

 out of the uterus into the vagina, the longitudinal muscles of 



Ann. & Mag. N. Hist. Ser. 5. Vol. xi. 8 



