MisceUancoHs. l» I .") 



The spidiK's are stiaifjht .•'li'iuler haeilli, bearing obtuse sjiiiios on 

 two of tlieir sides ; these are toU-rably hmg and of tlie same diameter 

 as the baeilUis itself. They are eoiisei|ueiitly very anah)gous in their 

 form to tliose of certain sjjecies of Cidarts, and especially to the 

 second of the forms represented in fig. 8 of the fiftli plate of my 

 memoir on the Kchinida. This figure represents various forms of 

 the spicules of a Jirisso/>sls from ^lexico. In Kcliiitonens there is 

 merely a greater homogeneity of form. 



Thus the Ec/iinonci, which in form and in the greater part ofllieir 

 characters are intermediate between the regular Echinidic and tlie 

 Spatangoidie, are eipially intermethate in the constitution of their 

 ambidacra. 



It is to l)e wished that those naturalists wlio possess irregular 

 Kchinida in a good state of preservation would till up the gaps whicli 

 I have been obliged to leave in my general work, at least if thev 

 are convinced that the pcdicellaritc and ambulacra can furnish good 

 characters, as I believe I have shown to be the case. — Annales des 

 Set. Xat. o^ ser. tome xiv. art. ">. 



Oil the Rej)rodHction of the Lophohraachs, and on the Filiation of 

 certain Genera, liy ^I. C'axi:stiuni. 



It is known that the males of these fishes, or at least of the 

 greater part of them, present cavities at the lower surface of the 

 tail, in the form of fossettes, or of sacs, in which the ova undergo 

 development, and in which the young remain for a certain time after 

 exclusion. ^M. Cancstrini has not been able, anj- more than the ich- 

 thyologists who preceded him, to actually sec the manner in which 

 the ova ai'rive in these receptacles ; nevertheless ho gives a suffi- 

 ciently plausible hypothesis, based on certain anatomical arrange- 

 ments. He supposes a sort of coition, in which, contrary to what is 

 seen in other cases, the female products pass into the body of the 

 male. The position of the sexual orifice of the female and that of 

 the opening of the ovigerous sac would facilitate this. In fact the 

 female sexual orifice looks downwards, and the orifice of the ovigerous 

 sac is directed upwards, so that, if an individual of each sex be 

 placed the one against the other, the female orifice will face the ori- 

 fice of the ovigerous sac and be able to discharge its ova into the 

 latter. It is probable that the prehensile tail of these animals also 

 plays a part (at least in the case of the jrq>pocamj)i)hj enabling the 

 two indi^'idual8 to hold each other closely united during this act, 

 which must last a certain time or else be repeated again and again. 

 The concourse of the sexes is evidently indispensable with the Ne- 

 ropkes, which have no pouch to receive the ova, but merely a scries 

 of fossettes at the surface of the belly, so shallow that no ovum could 

 remain there if it were not deposited in its place and fixed by an ad- 

 hesive substance. 



M. Canestrini thinks that the male fecundates the ova after they 

 have entered the ovigerous sac, the male sexual opening communi- 

 cating with that cavity by means of a duct formed at the expense of 



