6 Transactions of the Society. 



extent, and forming the largest and most conspicuous organs of the 

 body. The large ventriculus of Uropoda Krameri much more 

 resembles that of some of the Oribatid&e. It is true that in the latter 

 family also the cseca, although only two, are usually large, and form 

 much more important organs than in Uropoda Krameri ; but in the 

 typical forms of the genus Damseus [Oribatidse) the cseca are in 

 a similar condition, having become mere lobes of the ventriculus, even 

 less developed than in the Uropoda here spoken of. The ventriculus 

 is the " Mitteldarm " of Winkler. Kramer in 1876 * indicated 

 somewhat of this difference between Uropoda and Gamasus. Winkler 

 is inclined to deny it, but Winkler's Uropoda, which he speaks of as 

 having long caeca to the ventriculus, must be very different from 

 U. Krameri, of which species I have dissected large numbers, and 

 always found the ventriculus in the condition above described. 



There is not any small intestine in Uropoda Krameri ; the 

 colon proceeds direct from the ventriculus, arising from the ventral 

 surface of that organ, very near to, but not quite at, the posterior 

 margin. The colon is almost globular, but not quite, being slightly 

 elongated ; it is directed almost perpendicularly downward ; it is 

 sharply constricted, both anteriorly where it arises from the ventri- 

 culus, and posteriorly where it communicates with the rectum. 

 These constrictions are like gatherings-in of the walls of the canal, 

 appearing folded or wrinkled at these points as if a loose sack were 

 drawn in by a circular tie. A very short and narrow neck connects 

 the colon with the rectum ; it is this neck which receives the 

 Malpighian vessels, as mentioned hereafter. The rectum is very 

 similar to the colon, usually a trifle smaller and less globular in form ; 

 it is also less sharply constricted at the posterior end where it 

 surrounds the anus (fig. 8), which is a very small lenticular opening 

 in the chitin of the ventral plate. It can be closed by somewhat 

 chitinized folds of the inner cuticle, and is protected exteriorly by an 

 elliptical chitinous ring in the ventral plate ; this ring touches the 

 anal opening at the ends, but not at the sides. 



I have purposely left the above description of the hind-gut as 

 I wrote it before seeing Winkler's paper. I have adopted the same 

 nomenclature as I formerly employed relatively to the Orihatidse. 

 I find, however, that what I call the colon Winkler calls the hind- 

 gut (" Enddarm "), and what I call the rectum he also states to be 

 the rectum, but he usually calls it the excretionary collecting bladder 

 (" Sammelblase der Excretionorgane "), and he considers it to be a 

 portion of the excretionary system (Malpighian vessels), not of the 

 alimentary canal. 



It would probably be more convenient if words such as " rectum," 

 " colon," " oesophagus," &c., which are used in describing the higher 

 animals, were excluded from works on the lower creatures, such as the 

 Arthropoda, altogether; but if this be not done the question of 



* " Zur Naturgeschichte einiger Gattungen aus der Familie der Gamaeiden," 

 Arcliiv fiir Naturgesch., 1876, p. 63. 



