398 Miscellaneous. 



occupy tlie basilar region of the tentacles ; the otocysts rest upon 

 the pedal ganglia and are united to the cerebroid ganglia by two 

 very delicate nerves. Each otocyst contains a single large spherical 

 otolith. 



The author, in conclusion, notices a singular VorticeUidan Infu- 

 sorian of i)\Q germs ScypMdia, which occurred on the extremity of the 

 copulatory organ of several of his Truncatellce. The species of this 

 genus have hitherto been known onlj- from fresh water ; to this marine 

 species he gives the name of Scyphidia Fisclieri. It has a cylin- 

 drical body, slightly attenuated above ; its peristome is not much 

 reflexed ; and it has a broad and very thick foot, enabling it to 

 adhere strongly to the bodies on which it occurs. Its surface is 

 slightly striated in the direction of its length. These Infusoria move 

 very slowly. — Comptes Bendus, Sept. 7, 1885, p. 575. 



On tJie Development of Aurelia aurita and Cotylorhiza borbonica. 

 By Dr. A. Goxte. 



The first segmentations of the ovum produce neither exclusively 

 equal nor exclusively unequal blastomeres, but the two occur pro- 

 miscuously together. 



A ccelogastrula with a narrower or wider archenteron and a pro- 

 stoma always exists ; but, so far as I can see, is neve)^ produced 

 by invagination. There is rather in the coeloblastula a perfectly 

 irregular migration of endodermal cells into the blastocoeloma, so 

 that there originates from it a sterrogastrida of which the endoderm 

 becomes secondarily excavated (archenteron) and breaks out (pro- 

 stoma). By the closure of the prostoma and the development of 

 cilia on the ectoderm the ccelogastrula is converted into the larva 

 (plannla), which swims along with the vertical (aboral) pole for- 

 ward and attaches itself thereby. 



Before or after the attachment a sacciform invagination of the 

 ectoderm is produced at the prostomial end (Kowalevsky), and this 

 becomes the persistent ectodermal cesopliagus, which breaks through 

 into the stomach. At the same time the endoderm becomes saccu- 

 lated in the form of the finger of a glove at two opposite sides be- 

 tween the oesophagus and the ectoderm ; these first two gastral sacs 

 are continued downwards like grooves in the wall of the stomach, 

 two gastral folds being produced there in each case. Between the 

 two primary gastral sacs a new but broader gastral sac is formed on 

 each side ; and the four sacs surrounding the oesophagus at the same 

 time by their contiguity form four septa, which are continued down- 

 wards into the gastral folds. 



The tentacles grow forth above the gastral sacs, at first one over 

 each of the primary, and then three over each of the secondary sacs ; 

 of these latter (3-1-3) tentacles the four outer ones push forth each 

 in a septal plane. It is only at a later period that the four quad- 

 rants become equal in their dimensions and in number of tentacles. 



