260 72 



attenuated in front. It is extremely hyaline; very often I have found specimens 

 which, in contracted form, show a tendency to make lateral humps: when swimming, 

 they alw^ays disappear. The wheel-organ is constructed just as in A. priodonta and 

 so also is most probably the coronal disc, but owing to the slight material, I am 

 not quite sure upon this point. The most peculiar structure in tlie anatomy of the 

 species is that the long intestinal band, to which the testis is fastened in A. prio- 

 donta, is totally lacking here; the result hereof is that, whereas the testis in A. prio- 

 donta lies almost in the longitudinal axis of the body, in A. ßrzj/ftfu'eZ// it lies almost 

 transversally. Remains of the alimentan,' canal are totally absent in this species. The 

 brain and tlie two pairs of antenna? are constructed in accordance with that of A. 

 priodonta, but there is only a single eye lying upon the underside of the brain; not two 

 eyes in the ciliary wreath. The muscles are mainly in accordance with those of A. 

 priodonta. There are the same two pairs of strong longitudinal muscles, hauling in 

 the wheel-organ: the ventral pair is deeply cleft posteriorly, embracing with its two 

 parts the testis which is kept in place mainly by these muscles; very conspicuous 

 also are the much narrower muscles dorsaUy and ventrally, which take the same 

 position and have the same significance as in A. priodonta. A little behind the middle 

 we find the same spot dorsally as in this species, to which two longitudinal as well 

 as two slanting muscles with two other pairs running parallel, are fastened; to the 

 same point is further attached the downward directed muscle which with its other 

 end is fastened to the opening of the testis in the urogenital canal. Almost to the 

 same spots are also fastened two small muscles to the contractile vesicle. Apart 

 from the number of vibralile tags which, in this sex as in the female, is greater 

 (about lU) than in A. priodonta, I cannot find anj' difference with regard to the 

 excreton.- organ. The contractile vesicle may be very large. There is the same wide 

 meshed system of extremely fine threads under the cuticle; it seems, as if one of 

 the turning points in this system is just the point where the above-named many 

 stronger muscles meet. 1 have often observed that at the same moment when these 

 muscles are contracted, all the fine muscle threads are simultaneously contracted, and 

 the whole form of the posterior part of the body altered. Below the corona is a series 

 of small parallel muscle bands. The testis is almost globular; in the ductus seminalis, 

 and in the urogenital canal I find no differences from A. priodonta. In the testis are 

 found the two sorts of spermatozoa. It is rather pecuhar that, whereas A. priodonta 

 at the first glance is distinguishable from almost all other .4spZanc/jna-species, owing 

 to the globular ovarium, the ovarium being horseshoe-shaped in most of the others, 

 the testis in all species has quite the same globular form. 



It may further be added that, on the dorsal side of the animal we almost always 

 find some globular masses of very different size, form, and number. In my opinion 

 we have here rudiments of yolkmasses, in some way of nutrimental use to the 

 animal; they diminish during growth. They are mentioned by Dalrymple and are 

 indicated in the figure of Hudson-Gosse (1889. PI. XII, fig. 1 c). Size: male 166 — 

 200 /<, of female 500— 1500 ,«. 



