STUDIES OX THE EOTul'AKASlTlC TKE.MAl'UDES 0¥ JAPAN. HJ 



ill all the other speeie.s it open« into the genital atrium at various di.-^- 

 tances from its external opening (Pi. XXI. ûix. N; 1?J. XXII, up:. 2; 

 PI. XXV, figs. 3, S, aiKl !•). 



As ah'eady mentioned above, there are in this L;enu« two .sets of 

 nmscular lihres in the loose connective tissue ai'ound tlii' uterus, whidi 

 are exactly similar to, and one of which is the direct C(3ntinuation of, 

 those around the ootyp. The dorso-ventral hhres are present only a- 

 round the l(jwer part of the uterus; hut the horizontal fibres are con- 

 tinued to the margin of the 1jody. where they become continuous with 

 the diagonal fibres of the body (PI. XXII, fig. 4). 



A'itellakiu:m — This is a A^ery extensive organ situated mostly 

 in the lateral portions of the body and extending through the 

 greater part, or in some species throughout the whole lengtli, 

 of the body (Tn'stoinuin, EpihdeUa). In accordance with its position 

 in the body, it consists of two parts, a right and a left half, 

 which remain in many species entirely distinct throughout their 

 whole extent ; but in other species they pass into each other 

 at both ends. Again, in most species, the vitelhirium seems 

 to Ije closelv connected with the intestine in its arrangement, be- 

 ginning and ending with the main intestinal ti'unks. In Microcotijlo 

 this relation is especially C(jn.spicuous. As already mentioned, the 

 two trunks of the intestine are in some species of this genus of unequal 

 leno-ths : and then the halves of the vitellariiini also show a cor- 

 responding asymmetry, as in il/, clegrois (PI. I, fig. 4) and J/, sciacnœ 

 (PJ. II, fig. G). There are, however, also s})ecies in which the vitel- 

 larium and the intestinal trunks do not show any correspondence of 

 lengths, as }L caiuhla and Jl/. sclnisds (PI. I, figs. 1 & 2). Again, in 

 many species in whicli hiteral branches of the intestinal trunks are 

 given otf towards the median line, these are acctjinpanied by the vitel- 

 lai'ium, which then surrounds them on all sides. In Axine, Mtcrocotijle, 



