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PROCEEDINGS OF THE NATIONAL BIUSEUM. 



VOL. 39. 



Fig. 11.— Muscular system of Ergasilus versicolor in dor- 

 sal VIEW, a, Muscles moving first antenna; b to/, muscles 

 of enlarged second antennae; g to I, flexors of head 



AND first two thorax SEGMENTS', m, 0, AND T, MUSCLES MOV- 

 ING SWIMMING legs; m. 6, TRANSVERSE MUSCLE BAND; 71, FLEXOR 

 MUSCLES OF THIRD AND FOURTH THORAX SEGMENTS; p, MUS- 

 CLES CONTROLLING THE OPENING OF THE OVIDUCT; q, FLEXOR 

 MUSCLES OF FIFTH AND GENITAL SEGMENTS; S, FLEXOR MUSCLES 

 OF ABDOMEN, t, ACCESSORY MUSCLE OF SECOND ANTENNA. 



Here in the Ergasilidse 

 these plates are free 

 and are very manifestly 

 a part of the antennse. 

 They still perform the 

 same functions, being 

 partly tactile and partly 

 prehensile. And we 

 find them operated by 

 a pair of powerful 

 muscles (a) on either 

 side, corresponding in 

 position and function 

 with those which oper- 

 ate the frontal plates of 

 the CaligidsB. These 

 muscles are particularly 

 well developed in the 

 Bomolochime, where 

 the basal joints of the 

 antennse are consider- 

 ably enlarged, and even 

 in the opaque cephalo- 

 thorax of the mature 

 female they show up 

 prominently in dorsal 

 view. (PL 52, fig. 138.) 

 Behind these and par- 

 allel with them are three 

 pairs of strong muscles 

 (b), extending from the 

 mid-line diagonally out- 

 ward to the very edge 

 of the carapace. These 

 produce flexion of the 

 margin of the carapace 

 similar to that produced 

 by the corresponding 

 muscles in the Caligidse. 

 But there is not the 

 same freedom of mo- 

 tion here, since there 

 are no grooves be- 

 tween the cephalon and 

 the lateral areas, and 



