348 ANNUAL KECORD OF SCIENCE AND INDUSTRY. 



a complete ossification of the bones, the skeleton remaining 

 in a more or less cartilaginous state. 



LEPTOCEPHALI AEE LAEVAL FORMS OF CONGEES, ETC. 



Some years ago Dr. Theodore Gill pointed out, what had 

 not previously been even suspected, that the remarkable trans- 

 parent and elongated ribbon-like fishes, attaining a length 

 of several inches, and known as Leptocephali, were really im- 

 mature or larval forms of congers and related types. This 

 discovery, although received with some skepticism for a 

 short time, has been since universally recognized by European 

 and other naturalists. The observations of M. Dareste may 

 be co-ordinated with the previous ones, and find an explana- 

 tion for the raison cVttre in occasional persistence to a still 

 more advanced stao-e or throughout life of some characters- 

 tics which are normally in these forms protracted through a 

 considerable term of the early life of the fish. While the in- 

 completeness of ossification is persistent, however, the form 

 and most other characteristics of the normal adult congers 

 are attained, the only other known arrest of development af- 

 fecting the teeth, which do not attain the customary size. 



HAVE JELLY-FISHES A NEEVOUS SYSTEM ? 



The umbrella-shaped jelly-like organisms known as jelly- 

 fishes, or acalephs, which are almost always to be seen float- 

 ing near the surface of the sea, are, next to the so-called 

 Protozoans, the simplest forms of animal life, and the existence 

 of a nervous system has been regarded as extremely problem- 

 atical, and, indeed, denied by most authors. At the base of 

 the tentacles, which originate at equal distances from the 

 margins of the umbrella-like disk, or " rectocalyx," however, 

 there are minute vesicular-like bodies (called marginal vesi- 

 cles), which have been supposed by some zoologists (e.g., Agas- 

 siz, M'Crady, and Fritz Muller) to be the rudiments of a ner- 

 vous system. This supposition has received much support, 

 recently, from vivisectional experiments made by Mr. George 

 J. Romanes. Mr. Romanes's observations were made on the 

 acaleph known as Slabberia conica, a species about as large 

 as an acorn, and, as the specific name implies, having a conic 

 rectocalyx, from whose margin four tentacles originate ; at 

 the bases of these tentacles are vesicles smaller than the dot 



