232 B. H. Buxton, 



lias been reduced to a single one in each case, with the exception 

 of the primitive Theraphosid spiders which have two saccules still 

 remaining-, one on the third and the other on the fifth appendage. 

 The coxal glands of the Theraphosids have also two outlets corre- 

 sponding to the position of the two saccules, i. e. on the third and 

 fifth appendages, but all the other arachnids have but a single 

 outlet. 



In the scorpions and phalangids the outlet is at the base of 

 the fifth appendage, corresponding in position to that of Limulus. 

 In the true spiders (Araneae verae) and the Pedipalps the outlet 

 is on the third appendage and in the Solifugae on the second 

 appendage. My endeavor will be to demonstrate by means of 

 description and photographs that these conceptions of the arachnid 

 coxal gland are correct, and also to point out the various modi- 

 fications which the structure has undergone in the course of 

 specialisation. 



Almost all of the animals studied were collected by myself, 

 killed with chloroform, and immediately fixed in Duboscq's picro- 

 formal- acetic solution. Before fixation, the legs and abdomen were 

 cut oft' so as to allow of penetration of the fixing fluid into the 

 cephalothorax. Imbedding first in celloidin and then in paraffin was 

 found to be the best method for obtaining good serial sections, as 

 in this way the use of xylol is avoided and the chitin, always a 

 difficulty, does not become so brittle. Moreover, when the more deli- 

 cate tissues are padded with celloidin they do not become distorted 

 in the hot paraffin. 



For identification of the species I am indebted to Dr. Alex. 

 Petrunkevitch of Yale University to whom my best thanks are due. 

 A few specimens preserved in the ordinary way in alcohol were 

 also kindly provided by the late Prof. T. H. Montgomery, Prof. 

 Alex. Petrunkevitch and M. Eugene Simon of Paris, but naturally 

 sections from alcohol specimens are not often sufficiently well pre- 

 served for photography or for study of finer details. Where such 

 specimens are referred to they are indicated as such by (ale. spec.) 

 in brackets and the initial of the donor M., P., or S. The photo- 

 graphs were all taken direct from the sections and have not been 

 retouched. 



Before beginning an account of the special work done, it may 

 be well to explain in a general way the characteristics of the organs 



