Internal Anatomy of TJropoda Krameri. By A. D. Michael. 7 



nomenclature becomes somewhat arbitrary, and is probably of little 

 importance so long as it is clearly indicated exactly what the organs 

 are like ; but the question of whether the sack-like organ adjoining 

 the anus is a portion of the alimentary canal or of the Malpighian 

 vessels is possibly more substantial. There cannot be any doubt that 

 the organ in question is, so to speak, a cloaca, into which both the 

 systems discharge, and which conveys the excremental matter from 

 both to the anus. In the Gamasidm the amount of matter discharged 

 by the Malpighian vessels is large, and that furnished by the canal 

 is small compared to what it is in the Orihatidse and many other 

 families ; thus the former is sometimes in excess in the contents of 

 the organ in question. Herr Winkler also gives histological reasons 

 for considering this viscus to be part of the former system ; but ou 

 the other hand, the hind-gut of Uropoda Krameri, as I have so 

 frequently seen it, if this organ, which I call the rectum, be included 

 as part of it, agrees almost exactly with that of the Orihatidse ; in 

 which family the Malpighian vessels do not exist in this situation, and 

 do not communicate with this organ nor with the hind-gut at all. 

 Moreover, this rectum, as I call it, follows what I call the colon in the 

 ordinary manner in the species I am treating of, and constantly, 

 indeed usually, contains balls of the rejected portions of the digested 

 food, similar to those in the colon, and similar to those found in the 

 rectum of the Orihatidse; also it seems to me more consonant with 

 one's ordinary ideas to consider the viscus by which the alimentary 

 canal discharges to the anus as being the rectum in the usual sense 

 of the word. I think, therefore, that this organ should be regarded 

 as primarily a portion of the alimentary canal, although functioning 

 as a cloaca. I do not gather from Herr Winkler's description at what 

 exact point the canal and Malpighian vessels discharge into this organ, 

 which 1 call the "rectum," nor how the discharged matter passes 

 through it to reach the anus ; but if I understand his drawings 

 correctly, there must be some difference in these respects between his 

 species and Uropoda Krameri. 



The Excretory System. Fig. 8. 



This is entirely of the Gamasus type, and does not in any way 

 resemble that of the Orihatidse ; it consists of two very long sack-like 

 organs, which may probably be correctly called Malpighian vessels 

 (fig. 7, mv) ; they are arranged bilaterally, one on each side of the 

 body, and are usually more or less filled with opaque white excre- 

 mental matter from end to end. These vessels arise, one on each 

 side, from the narrow neck of the alimentary canal which connects 

 the colon with the rectum. Each vessel commences with a short 

 tubular portion of small diameter (fig. 8, mv^), which, indeed, is a 

 necessity to enable it to spring from the very constricted part of the 

 alimentary canal where it is placed. This narrow part leads into an 

 elliptical chamber (m v^), which is far the largest portion of the 



