536 



MR. F. M. CAMPBELL ON A PROBABLE 



of the hypopharyngeal and peripharyngeal grooves. 6. The oesopha- 

 geal aperture &c., magnified. 7. Dorsal tubercle, magnified. 8. Con- 

 cretions from the renal organ. 



Explanation of the Lettering. 



d. I., the dorsal lamina. 



d. t., the dorsal tubercle. 



en., endostyle. 



h. m., the horizontal membrane of the 



branchial sac. 

 %., intestine. 



i. I., internal longitudinal bar. 

 n.g., the nerve-ganglion. 

 ov., the genital glands. 



p. a., peritubercular area. 



p.p., peripharyngeal bands. 



ren., renal organ. 



sg., the stigmata of the branchial sac. 



St., stomach. 



tn., tn.', tn.", tentacles. 



tr., tr.', tr.", the transverse vessels of 



the bi-anchial sac. 

 2,, the zona prsebranchialis. 



On a probable Case of Parthenogenesis in the House-Spider, 

 {Tegenaria Crwyonii). By F. Maule Campbell, F.L.S. 

 [Eead June 15, 1882.] 

 For some years past I have confined Spiders with the view of ob- 

 serving their habits. During the autumn of 1878 I imprisoned an 

 adult female Tegenaria Guyonii, Gruerin ( = T. domestica, Blackw.), 

 just after her last moult. In the following May she laid eggs, 

 which were hatched ; and as her capture had followed so closely 

 on the adult stage, I could scarcely think she had been fecun- 

 dated, and suspected that the cause of fertility was agamic re- 

 production. 



In the autumn of 1880 I confined three females of the same 

 species as above, having previously satisfied myself as to their 

 immaturity. They moulted successfully at the end of September ; 

 but two died during the winter, and the third (May 1881) laid 

 eggs whicli were non-productive. During the same month the 

 first-mentioned Spider, a few days prior to death, made a cocoon, 

 with the same result. The eggs became shrivelled and hard, 

 while a few retained nearly their original form, but turned green- 

 black in colour. A female (T. Guyonii, Guerin) which I had 

 caught adult in December 1880, gave me in July 1881 a large 

 brood. In May 1881 I confined two immature females of the 

 same species. Both cast their skins twice, the last occasion 

 being in September. One died during the winter; and the 

 other has afibrded the material for this paper. 



I kept this Spider like the others, each one in a separate flint- 

 glass bottle, 4^ inches high from shoulder to base, and 4 inches 

 in diameter ; I covered the mouth with a glass slip. As soon as 

 she became accustomed to her prison, she began to fasten threads. 



