498 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
are nevertheless comparable in different forms. The range in their 
characters appears to point out a broad path leading from the shark-like 
type of Lepidosteus to the Teleostean type of Amia. These Teleostean 
features of Amia permit no other conclusion than that the Ganoidean 
plan of development may become that of the bony-fishes — the sought-for 
ground on the side of embryology for the linking of the later evolved 
Teleost to the ancient Ganoid. The elasmobranch features of the 
embryonic Lepidosteus might, perhaps, be looked upon as suggesting 
the line of descent of this ancient Ganoid. The wide range in the 
modes of development of the Oyprinodonts, a group which cau be given 
no higher rank than that of a family, must be accepted as the clearest 
proof of what little phylogenetic importance can be strictly claimed for 
differences in ontogeny. 
Development of Bdeliostoma.* — Mr. G. C. Price has studied some 
points in the development of Bdellostoma Stouti Lockington. The 
elongated cylindrical eggs measure about 22 mm. by 8 mm. ; the shell 
is brown and liorn-like with liook-bearing polar threads ; there is a 
circular lid at the anterior pole. 
The first observed embryonic stage was in many ways Teleostean- 
like, and showed no external openings. The nario-hypophysial canal 
was blind at both ends, and paired olfactory sacs opened into it, as well 
as a narrow canal from the front of the gut. Thirteen pairs of unopened 
gill-pockets were present, the most anterior being apparently hyo- 
mandibular. 
In the next stage the paired evaginations of the nario-hypophysial 
canal, which form the nose, are secondarily subdivided by three or four 
plaits on each side. The connection between the canal and the gut is 
lost, and a minute external aperture appears. 
The third stage shows four pairs of tentacles, a posterior opening 
between nasal canal and gut, and 11 pairs of gill-pockets in the segments 
corresponding to spinal ganglia 19-29. 
In the first stage the pronephros is seen far forwards and extends 
through 69 segments, in the third stage all traces have disappeared in 
the first 20 of these. What Weldon distinguished as pronephric and 
mesonephric regions are differentiated from a quite continuous and 
uniform rudiment. 
Egg of Amphioxus.t — Dr. 0. Van der Stricht gives an account of 
the early stages of the egg of Amphioxus. He points out that it is 
a material in which the study of very many interesting phenomena is 
exceedingly difficult. The colouring matter is not only small in quantity, 
but stains feebly, and the centrosomes, if they exist, are difficult to 
distinguish from the granulations of the yolk. Another difficulty which 
one has to encounter is the frequency of polyspermy, which sometimes 
gives rise to very embarrassing images. The memoir, which appears to 
deal with details only, discusses (1) the structure of the ovarian egg 
before it is laid, (2) the appearance of the male and female pronucleus 
after oviposition, and (3) the fusion of the pronuclei and the division of 
the first segmentation-sphere. 
* SB. K. B. Akad. "Wiss. Miinchen, 189G, pp. 69-71. 
f Arch, dc Biol., xiv. (1896) pp. 469-95 (2 p’s,). 
