346 ON A HERMAPHRODITE AND 



However this may be, these sacs are clearly homologous with the 

 curious sacs which have been described in Chloi-csina, and perhaps 

 with the sacs opening externally, which are found in the anterior 

 segment of Pectinaria. 



I may mention here that ciliated organs, possibly homologous 

 with these, and with the lateral convoluted canals of the Linnbricidcz 

 and Hirudinidm are by no means uncommon among the Annelida 

 Errantia, and may be observed in Pliyllodoce ; it requires care 

 however to discover them. 



Nervous sj'stein. — On this head the result of my examinations 

 was exceedingly unsatisfactory, as I could assure myself of the 

 existence of only two oval ganglia, one on each side of the oesophagus,, 

 each of which presented a dark pigment mass (eyespot ?) on its 

 anterior extremity. 



Reprodtictive elements. — Protula Dysteri can hardly be said to 

 possess special reproductive organs, the reproductive elements, viz.,, 

 ova and spermatozoa, being developed as it were accidentally from 

 the walls of the perivisceral cavity, by the fluid contained in which 

 (whose nature and importance M. de Quatrefages has so well pointed 

 out) they are bathed, and supplied with nutritive materials. It 

 appeared to me that the spermatozoa or ova took their origin in 

 granular thickenings of that portion of the face of the dissepiments 

 which is traversed by the transverse vessel, becoming detached 

 thence, and floating freely in the perivisceral fluid, as they attained 

 their full development.^ 



The youngest spermatozoa were minute spherules, of not more 

 than ^-nVo- of ^n inch in diameter, aggregated together into irregular 

 masses (fig. ii). In a more advanced state a very fine short and 

 delicate filament could be observed springing from one side of this 

 body. By degrees the spherule became elliptical, and narrowing 

 ■ba7-i passu with the elongation and thickening of the filament, the 

 ultimate result was a spermatozoon, such as that represented in fig. 

 II, with a subcylindrical slightly pointed head of -g-Juo- of an inch in 

 diameter, and a very long actively-undulating tail. 



The ova are, at first, very small, not more than ^-qVo" of an inch in 

 diameter, and possess a relatively very large, clear space, representing 

 the germinal vesicles, containing a minute germinal spot. By degrees 

 they increase in size to -j-J-^- inch, with a germinal vesicle of YuVd> ^-^d 



^ Frey and Leiickart (Zool. Untersuchungen, p. 88) assert that the generative elements of 

 the annehds are developed from a free blastema, and not from the septa only, as Krohn 

 asserts to be the case in Alciope, and as I should, from what is stated above, bo disposed to 

 believe. 



