1895.] HYDEACHNID FOTJlirD IS COBlfWAlL. 187 



it overlies and touches the ventriculus for a considerable distance, 

 yet I am utterly unable to find any sign of a communication 

 between the two. There is not any point where the outer coat of 

 the excretory organ becomes vague as in Henkin's TromhicHum. I 

 have carefully examined sections, cut in all directions, with high 

 powers, and the tunica propria appears continuous and most 

 distinct everywhere, and in some specimens the two organs do not 

 quite touch anywhere, there being a distinct space between vciih 

 connective tissue joining them. I know how difiicult it is some- 

 times to detect communications, and therefore I will not absolutely 

 deny that anything of the kind exists : but I am decidedly of 

 opinion, however improbable it may seem, that it is true that the 

 mid-gut ends blindly, and that the excretory viscus which ends in 

 the anus-like opening (fig. Ki, A.) has not any communication with 

 the mid-gut. The improbability is diminished when we consider 

 that these creatures do not swallow any solid food, but live entirely 

 by suction, feeding on the blood of other minute creatures which 

 they capture ; still, of course, a Spider or a Gamasid lives in the 

 same way, but has a distinct hind-gut and anus. In the present 

 instance, however, I have not ever seen food in the organ, as we 

 should expect to do if it were in direct communication with the 

 ventriculus ; I find the white excretory matter and that only. 



AVith regard to the homologies of the organ, if it were not for 

 Schaub's species, I should say that it appeared to me that the 

 anus-like opening was the true anus, and tliat the excretory organ 

 which leads to it was the horaologue of the hind-gut ; although in 

 consequence of the nature of the food, or for some other reason, 

 the hind-gut had become severed from the mid-gut and had lost its 

 function as a hind-gut, assuming that of the Malpighian vessels 

 found in Gamasidae, &c. I have not ever seen Schaub's species : 

 but if we can rely, as we naturally suppose we may, upon his 

 inA^estigations, which I believe were conducted in Professor Cohn's 

 laboratory at Vierma, then the presence in so closely allied a 

 species of a second anal opening, and of a well-marked and 

 functional hind-gut, in addition to the excretory organ and 

 opening, would seem to prove beyond question that in other 

 species, such as the present one, the hind-gut and anus have 

 become obsolete, and that the excretory organ is of the nature of a 

 Malpighian vessel, or at all events of the organs which bear that 

 name, whether properly or not, in the Gamasidfe, &c, and in many 

 other Arachnida, e. g. Mijgale, &c., although it discharges to the 

 exterior instead of into the hind-gut between the colon and the 

 rectum, which is the point of discharge in Gamasidse, &c. 



The form of the excretory organ (fig. 15, and figs. 14, 23, E.) is 

 very much that shown by Schaub, viz. an elongated sac with a 

 rounded, csecal, anterior extremity, varying and irregular in its 

 diameter, but widening out so as to form a pyriform expansion 

 before it suddenly narrows to reach its point of discharge. This 

 Avidened part is generally compressed dorso-ventrally by folding 

 and compression. These folds are quite irregular and do not 



