64 DRS. CARPENTER AND CLAPAREDE ON TOMOPTERIS ONISCIFORMIS. 



A considerable number of males came under our notice before we met with any 

 specimens whose female sexuality was indicated by the presence of ova : of these, how- 

 ever, we subsequently encountered several ; and our observations on them are in accord- 

 ance with those previously made by Huxley, Busch, and Leuckart and Pagenstecher. 

 In a mature female (fig. 1) the ova are to be seen lying, in great numbers and in 

 various stages of development, in every part of the perivisceral cavity of the body and 

 of its caudal prolongation, and also in the extensions of that cavity into the lateral 

 appendages, including even the basal portion of the second antenna?. From a compa- 

 rison of the conditions under which they may be seen in one and the same individual, 

 it becomes obvious that they originate in the terminal wall of the cavity of the pin- 

 nulated appendages, — a fact that seems to have been first recorded by Drs. Leuckart and 

 Pagenstecher, though we learn from Mr. Huxley that he had arrived at the same con- 

 clusion ten years ago. This terminal wall, which gives support on its outer side to the 

 bases of the pinnulse, presents on its inner surface a number of transparent tubercular 

 elevations (fig. 7. <?), which progressively become hemispherical, then pear-shaped, and 

 finally give exit to peculiar nucleated cells Avhich float in the fluid of the perivisceral 

 cavity. These cells multiply by self-division after the ordinary mode (fig. 13) ; and it is 

 only after their number has thus been considerably augmented, that they begin to increase 

 in size and to assume the characteristic appearance of ova. It is not only in the lateral 

 appendages of the body, however, that ova thus originate ; for it is clear to us that they 

 are developed also in the caudal prolongation ; and it would seem probable (though we 

 could not satisfy ourselves of the fact) that they there originate in the corresponding 

 situation — that is, on the terminal walls of those extensions of the perivisceral cavity into 

 the rudimentary appendages, which, as just shown, are the seat of the testes in the male. 



It is a fact not to be passed without mention, that rudimentary ovaria are to be seen 

 in mature males, — the terminal walls of the lateral appendages of the body presenting 

 those tubercular elevations whose presence constitutes the first stage in the development of 

 ova in the female. Whether at some other period these may develope ova (as is the case 

 with certain other worms, which are really hermaphrodite, but which mature their male 

 and their female products at different periods), or whether they are merely persistent 

 rudiments not destined to undergo any further dcA^elopment (like the mammary glands of 

 the male mammal), is a question to be determined by future observation. 



We have not been able to detect the mode in which the ova make their exit from the 

 body, — the transverse fissures in the outer wall of the perivisceral cavity, which are de- 

 scribed by Leuckart and Pagenstecher as presenting themselves in the third and fourth 

 segments, not having been noticed by us, probably because they had not yet been formed. 

 Nor have we been able to satisfy ourselves whether the ova are fecundated before their 

 escape, by the entrance of spermatozoa through the cihated canals into the perivisceral 

 cavity, or whether they receive the fertilizing influence after their emergence. 



Although we have had no opjDortunity of following out the development of this inter- 

 esting creature ab ovo, yet it has been the good fortune of one of us to capture, off the 

 coast of Skye, what we cannot doubt, from the conformity of its general organization to 

 the type we have been describing, to be a very early form of the same Tomopteris. This 



