1 882.] Zoology. 739 



if it is a good thing for people to " jump into a wagon and all take 

 a ride," why don't the same rule apply to black cats ? He 

 would come pretty near accepting a railroad pass. — Charles Aid- 

 rich, Webster city, larva , Jan. _? / , 1882. 



Development of the Sturgeon and the Homologies of the 

 Vertebrate Brain.— In a second paper by Salensky on the em- 

 bryology of the sturgeon, according to the Journal of the Royal 

 Microscopical Society, the author after describing the mode of 

 development of the central nervous system, raises the question of 

 the homology of this region with the nervous system of Vermes 

 and Arthropoda. He points out that (1) the central nervous sys- 

 tem of all vertebrates is formed from two thickenings of the ecto- 

 derm set parallel to the long axis of the body ; that of all articu- 

 lates has a similar origin. (2) In some cases, e. %. Echiurus, the 

 articulates present a median groove comparable to that of verte- 

 brates. (3) The formation of the medullary groove begins, in 

 the case of both phyla, posteriorly, and is continued forwards. 

 On the other hand the Vertebrata have the central nervous sys- 

 tem dorsal in position, and the medullary groove becomes closed. 

 As to the first of these, Salensky points out that the position of 

 the mouth is the determining character in conjunction with that 

 of the locomotor organs ; these poitits he looks upon as having 

 less morphological value than the development of the system, 

 and its correlation with other organs during the course of devel- 

 opment. The closure of the medullary groove is regarded as 

 being merely the result of further modifications. 



If we accept the general homology, we have next to determine 

 how the parts correspond ; the author cannot follow Dohrn and 

 Hatschek in regarding the homology as being complete ; he 

 looks upon the brain of vertebrates as being a new formation, 

 which is their exclusive property; it merely consists in an elon- 

 gation and dilatation of the already existing nervous system, or 

 in other words the medulla, which is the analogue of the ventral 

 ganglionic chain of the Articulata. 



Recent progress in the Study of Worms.-— Several papers 

 devoted to the higher worms, of a high order and with excellent 

 illustrations, have lately appeared in Germany. The develop- 

 ment of Polygordius ami kiccocinus, two low chaetopods has 

 been described by Repiachoff. The Gephyrean worms have, how- 

 ever, received special attention. In an elaborate memoir on the 

 Echiurida in the Nova Acta of Halle, by Professor Greef, the 

 anatomy of the i-roup is discussed with fullness, aided by colored 

 drawings of transverse stained sections. The presence of a 



that it is a remnant of the ectodermal invagination. A full ac- 

 count is also given of the curiously minute male of Bonelha. The 

 author thinks that there is no close genetic affinity between the 



