] 2 Transactions of the Society. 



The penis and accessory organs. — Taking Nothrus theleproctus 

 as an example, the penis is a small cbitinous organ, broader near 

 the distal than the proximal end, but almost pointed at eacb, the 

 distal end being bulbous (plate II. fig. 3). Near this end there 

 is a cbitinous process to which the retractor and extensor muscles 

 are attached. This penis, when retracted, rests in, and is protected 

 by, a second cbitinous piece (plate II. fig. 2), which is concave, 

 like half a tube (cut longitudinally) ; the distal end, however, is 

 closed by a semicircular return, or turning-up, of the half-tube, 

 so as to form a shallow pocket, in the edge of which is a notch, 

 evidently as a guide to the penis when protruded. The walls of 

 the proximal portion of tbe half-tube are turned outward and 

 expanded, so as to form pyriform blades, doubtless with the object 

 of afibrding a firmer attachment. 



The whole arrangement, when not in action, is retracted within 

 a membranous sheath, which is retained in an open or distended 

 condition by two curved cbitinous pieces (plate II. fig. 2). The 

 penis is, of course, in communication with the ductas ejaculatorius. 

 This intromittent organ and its adjuncts bear a striking resemblance 

 to those of Carahus glahratus, &c., in the Coleoptera : the drawing 

 of the penis of one would almost serve for the other ; the mem- 

 branous tube is Burmeister's pra^putium, and the cbitinous j)iece3 

 are his horny ridges, or bones, distending the same. The whole 

 of the male organs above described, particularly the testis, vasa 

 dcferentia, &c., have a marked similarity to those described by 

 A. Cronberg for Nessea coccinea.* 



The copulative suckers, genital plates, &c., have already been 

 well described by Nicolet. 



As far as I have been able to observe, the spermatozoa are not 

 mobile or flagellate. I have succeeded in obtaining them from 

 Dam [BUS geniculatus by breaking up the testis, and also by pressing 

 the part which appeared to me to act as vesicula seminalis, almost 

 immediately after death ; they are small, ellij^tical, highly refractive, 

 bodies, about the l-10,000th of an inch in the long axis ; they are 

 figured in plate II. fig. 4, highly magnified. They closely resemble, 

 except as to size, the semen of Tegenaria giiyonii Guerin, one of the 

 spiders which were shown to me by F. M. Campbell, of Hoddesdon ; 

 these were non-flagellate, although some spiders appear to have 

 flagellate semen. Blane figures the semen of Phalangium cornu- 

 tum and other species as non-flagellate. f 



The Female Organs of Generation. — The general arrangement 

 and position of tliese, as before stated, greatly resemble those of 

 the male; it is, however, unnecessary to say that the differences 

 are numerous and important. The organs consist of the ovary, 



* 'On ICi/lais cxtcndcns,' Moscow, 1878 (in Kussiaii). 

 t Bull. Soc. Vaud. de Sci. Nat., xvii. pi. (j, fig.. 23. 



