262 74 



The coronal disc is conical with two apices. The cilian' wreath is a simple 

 ring of cilia, as far as I have been able to see without any interruption either dor- 

 sally or Tcntrally. The brain is large, flattened; when the animal, as the figure shows, 

 is seen laterally, pear-shaped. On the coronal disc are found two hairtufls, and each 

 of these receives nerves from the brain; four long nerves, two ventrally and two 

 dorsally. run down to the two pairs of antennæ; there is only one red eye and no eye 

 spots in the corona. As in A. Brightwelli it is not possible to point out the slightest 

 trace of an intestinal band; the testis is only fastened by muscles, and here also 

 has an almost transversal position. 



With regard to the muscular system it will be seen by comparison with the 

 figures of A. priodonta and A. BrightøeUi that especially with regard to the great 

 retractors of the wheel-organ, the slanting transversal muscles, and some of the 

 muscles to the penis, there is a great resemblance in all three species. There is only 

 this diSerence, that ventrally we find a rather large muscle, fastened upon the testis 

 and running up to the wheel-organ; this muscle has no congruent in the two other 

 species. Peculiar too is the much coarser equipment of fine muscle threads below the 

 cuticle; further that these threads almost run parallel and are especially developed 

 in the hind part of the body: it is on this system of cuticular muscles that the al- 

 most incredible variation in outer form in the first line depends. In specimens, de- 

 riving from the locality where the species was first found, a ven." little duck pond 

 belonging to a little farm a few küom. from Hillerod, this system of muscle threads 

 was very conspicuous: this was also the case with the specimens deriving from the 

 duck pond in the little village of Fjenneslev near Soro. In the vascular system two 

 sorts of canals are distinguished, the one very large and long forming windings and 

 slings, the other more straight carrying in a long row at all events more than thirty 

 vibratile tags and perhaps more. Leydig (1855, p. 27) mentions about 50, Hudson- 

 Gosse often more than forty (1SS9. p. 122). The contractile vesicle when fully dis- 

 tended, occupies a very large part of the body cavity: it is co\ered with a conspi- 

 cuous muscular network, the muscle threads meeting each other in two opposite points. 



The testis is pear-shaped and very hke that of .4. Brightwelli; it is as always in 

 the Asplanchnas rather small in comparison with the size of the animal. The ductus 

 seminalis and urogenital canal are formed quite as in the other species ; on the 

 sides of the canal are a series of glands which may be regarded as prostata glands; 

 similar ones I think I have seen in .4. Brightwelli, but not so conspicuous as here. 



Especially in the middle of the body and near the sleeve-Kke prolongations 

 but also otherwise we find peculiar irregular bodies also mentioned by Leydig. He 

 is of opinion "dass diese Masse ein Rudiment des Zellenmaterials ist, welches beim 

 Embryo zum AutTjau des Magens bestimmt wird, aber da einmal die Männchen ohne 

 Nahrungskanal sein sollen, nicht zum Verbrauch kommt". 1 agree with Leydig in 

 the first part of this sentence, but am not quite sure that this store nutriment is of 

 no significance for the animal. Size of male 250 — 300//, of female 600 — 1000 /j. 



.4. Sieboldi (= .4. Ebbesborni) seems to be a ver\- rare animal in our country. 



