316 KANSAS UNIVERSITY SCIENCE BULLETIN. 



glands, apparently because he has concluded that all fetid and 

 anal glands are repulsive. 



As far as the position, size and structure of these glands are 

 concerned, these earlier observers are on the whole correct. 

 They agree, too, in the main points, Dufour has the glands 

 attached to the rectum, while Fenard has them attached to the 

 genital duct. The explanation of this difference of observation 

 is partially suggested by Fenard, when he says: ''En somme 

 ces organes paraissent d'eboucher dans une sorte de cloaque ou 

 arrive I'oviducte." The mole crickets have but a single opening 

 at the posterior end of the abdomen ; and a short common duct 

 carries the genital and excrementary products. This should 

 very properly be called a "cloaca." Into this cavity the short 

 ducts of the anal glands empty. 



Fenard gives as the sizes of the glands "about six millimeters 

 in length and three millimeters in thickness." I found none 

 as large as that, but the size would depend in part upon the 

 amount of secretion in the gland. Both Dufour and Fenard 

 speak of two lobes and a median constriction. There is some 

 tendency for such a constriction to show, but it is not constant. 

 The shape and position of the organ would depend somewhat 

 on the amount of extension of the abdomen and the full- 

 ness of the rectum. The two lobes when present do not differ 

 in histological structure, and not in function, as Fenard has 

 shown by his careful work by means of sections. The 

 walls are resistant, the cavity large, and the contents appear 

 homogeneous, granular, and they coagulate as a result of fix- 

 ation, and color strongly whenever stained. All these facts 

 Fenard has correctly described. 



But Fenard must have worked with preserved specimens 

 only, or he would not have made the error concerning the func- 

 tion of the gland. Although he quotes Dufour, he cannot have 

 followed his suggestion when the latter says : "If one seizes 

 a mole cricket of either sex, it squirts from the anus a brown 

 liquid of nauseating fetidity. This liquid is formed in part by 

 excrement from the rectum and is in part the product of a 

 special secretion." 



I have studied Scapte^iscus didactijlus from Porto Rico and 

 Gryllotalpa borealis taken in northern Indiana and in eastern 

 Kansas. My observations and experiments show that the above 

 quotation is correct in most parts. If the insect is held or irri- 

 tated in the region of the head or thorax, there is no discharge. 



