298 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



''The 'glandular mucosa' [Zenker's organ] consists of a central 

 cylinder, closely beset with radiating filaments, arranged in 50 to 60 

 transverse rows, the whole organ being imbedded in a sort of glairy 

 matrix. The two glands are connected each by an efferent duct with 

 the ^ bursa coimlatrioc,' an organ of very complicated structure, and con- 

 sisting of a much convoluted canal {Ivesicula seminalis), an intromittant 

 organ ov penis, and two hooked appendages. The whole organ is very 

 dense in structure, consisting probably of chitin, deep brown in color, 

 and, with the 'glandulee mucosae,' constitutes a very considerable por- 

 tion of the male carapace. It should be noted that the ' bursa copula- 

 trix,^ as well as the testis,* is a double organ, one on each side of the 

 median line. The two burssp. lie closely in apposition but are not in 

 organic connection except at the upper margin, where they are held 

 together by a ligamentous tissue. Length 2^:^ in. (1.1 mm.), height 

 JL in. (0.78 mm.)." Habitat: Minnesota (Herrick '85). 



GENUS CANDONA Baird. 1850. 



This genus, which was founded by Professor Baird (5) has recently 

 been more restricted by Mr. Wenzel Vavra (221). In this connection 

 the genus is used in Vavra' s restricted sense. 



In the female the antenna is five-jointed. In the male, owing to a 

 division of the fourth joint, the antenna is six jointed. At the division 

 between the fourth and fifth joints of the male antenna two character- 

 istic olfactory hairs are situated. The distal extremity of the third 

 joint is not supplied with a brush of natatory setse. The rudimentary 

 branchial plate of the second maxilla is composed of two, unequal, 

 pectinated set*, which are attached directly to the basal portion of the 

 maxilla. In the female the palp of this maxilla is two-jointed, and 

 terminates with three unequal pectinated bristles. In the male this 

 palp, which is then unjointed, diifers in shape from that of the female- 



The second foot, which may be either five or six-jointed, terminates 

 with three setse; two unequally long, backwardly directed, setse and 

 one forwardly directed seta. 



The strong post-abdomen (abdominal ramus) bears two terminal 

 claws. The seta on the caudal border of the ramus is quite remote 

 from the end. At the origin of this ramus the dorsum of the body 

 terminates in a short seta. The eye is small. 



Males are common, larger than the females. 



Seven circles of chitinous spines are arranged around the central 

 cylinder of Zenker's organ. The copulative organ is not so complex 

 as that of Notodromas. 



*Dr. Brady uses testis as a synonym for Zenker's organ. It is now well known that this organ is not 

 the testis. 



