444 MR. LUBBOCK ON THE THYSANURA. 



My examination of Smynthurus began early in October. At this period tbe ovaries 

 generally contained perfectly clear jelly-like nuclei, of which the largest were about 

 "OOl" in diameter, but many were much smaller ; these nuclei were surrounded by a 

 clear, transparent, but less brilliant substance, which sometimes formed a complete 

 spherical envelope to a single nucleus, but generally appeared as a lobulated mass 

 enclosing two or more. In other cases, which I suppose were more advanced, the nuclei 

 were darkened by a deposit of granules. Even, however, early in October the development 

 of the eggs was sometimes much more forward, aiid the ovary contained a number of yelk- 

 masses at pretty regular intervals. In a transverse section of the ovary there were three, 

 or at the broadest part four rows. The spaces between the yelk-masses were occupied, 

 as before, by the nuclei and their transparent enveloping substance. The yelk-masses 

 having at this period no bounding membrane, when I attempted to isolate them by open- 

 ing the ovary, they immediately fell to pieces ; which made the study of theu* develop- 

 ment somewhat difficult. On the 13th October I found a specimen with eggs apparently 

 ready to be laid ; they were yellow, round bodies, -01" in diameter, with a single struc- 

 tureless ovarian membrane, and the yelk was composed of oil-globules of various sizes 

 up to -0015". I could iind no trace of Purkinjean vesicle. On the 22nd I exa- 

 mined another female in a similar condition, and found the eggs to be about forty in 

 number. 



Male Generative Organs. — SmyntMrm Buskii, as I have already observed, became 

 much rarer in the latter part of November, and disappeared altogether early in December. 

 Up to this time I had been occupied in the determination of species and the examination 

 of the other parts ; so that my description of the male organs of reproduction must be 

 taken from Fapirms Saundersii, which made its appearance later in the autumn, and 

 lived longer through the winter. There is, however, no doubt that, if my specimens had 

 lasted, I should have been able to lay before the Society a description of these organs in 

 Smynthurus Buskii, which, from its greater size, was the species most favourable for 

 dissection. 



In Fapirius Saundersii, as in many other apterous Articulata, the testis is formed 

 on the same type as the ovary. On each side of the body is a simple tube (PI. XLVI. 

 fig. 38 a), opening into a triangular reservoir with its base in front. The two posterior 

 sides of the triangle are accompanied by a glandular accessory organ, containing a central 

 cavity (PI. XLVI. fig. 38 c), full of minute globules, the largest of which do not exceed 

 •000083" in diameter, while the majority were much smaller. Prom the posterior angle 

 of the reservoir a short and narrow vas deferens runs into the ductus ejaculatorius, 

 which is also short pyriform, and opens, like the vulva, with the anus at the posterior 

 end of the body. 



The development of the spermatozoa proceeds as in Obisium (Phil. Trans. 1861). 

 The testis contains small cells, about -00025" in length, and collected into masses of 

 various sizes, which have probably arisen within mother-cells ; their size does not 

 appear to depend in any way on the stage of development of the spermatozoa. The 

 small cells which compose them are at first somewhat oval ; gradually one end elongates, 

 and at length they resemble in form the egg of a Cynips, consisting of a thread, with 



