732 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
(5) The bottom-fauna soon produced progressive development among 
pelagic animals. 
(6) After the establishment of the bottom fauna, elaboration and 
differentiation among the representatives of each primitive type soon set 
in, and led to the extinction of the connecting forms. 
The origin of the Chordata is next considered in its relation to 
pelagic influences, and the essay concludes with some observations on 
the origin of the Craspedota, which, says the author, “ notwithstanding 
the text-books, I regard as a product of pelagic influences.” 
Neuro-hypophysial System of Tunicates.* — In the second of his 
“ Studies on the Protochordata,” Mr. A. Willey deals with the develop- 
ment of the neuro-hypophysial system in Ciona intestinalis and Clavelina 
lepadiformis, and gives an account of the origin of the sense-organs in 
Ascidia mentula. In Clavelina the permanent ganglion begins to be 
formed at a stage which is relatively much earlier than in Ciona , and, 
in fact, before the atrophy of the cerebral vesicle. From the first, too, 
it is a solid structure. 
It would appear that in all Ascidians the lumen of the hypo- 
physis is at first in direct communication with the lumen of the central 
nervous system ; this forms a great and instructive difference between 
the development of the hypophysis in the Ascidians and in the higher 
Vertebrates. The permanent separation of the two parts of the hypo- 
physis cerebri in the higher Vertebrates may be compared with the 
temporary obliteration of the lumen between the proximal and distal 
portions of the hypophysis which obtains in Ciona. The facts of 
development support the suggestion of Julin and Balfour that the 
subneural gland and dorsal tubercle of the Ascidians are homologous 
with the pituitary body of the higher Vertebrates. 
Position of Mouth in Larvae of Ascidians. In his third “ study,” 
Mr. Willey discusses the position of the mouth in the larvae of Asci- 
dians and Amjphioxus, and its relation to the neuropore. Although the 
mouth of the larva of Amjphioxus occupies an intermediate position 
between that which it holds in the Ascidian larva and in Balanoglossus , 
it certainly does not represent an intermediate stage. There is no 
evidence to lead us to suppose that the mouth of Balanoglossus has 
migrated from a dorsal to a ventral position ; it is probable that both its 
mouth and that of Ascidians were originally terminal in position ; the 
primitive vertebrate mouth, before the cranial flexure had become an 
established feature in the ontogeny, was probably dorsal or dorso-terminal 
in position. In the common ancestor of the Urochorda and Cephalo- 
chorda the mouth was, no doubt, in intimate relation with the neuropore, 
probably through the intermediation of a ciliated funnel or hypophysis. 
j3. Bryozoa. 
Marine Bryozoa. :{ — In another part of his “ Appendix ” to his con- 
tributions on these animals, the Rev. T. Hincks remarks that his genus 
Pedicellinojjsis is not to be separated from Barentsia ; his Cyclicojpora 
* Quart. Journ. Micr. Sci., xxxv. (1893) pp. 295-316 and 329-33 (2 pis.). 
t Tom. cit, pp. 316-33 (1 pi.). 
% Ann. and Mag. Nat. Hist., xii. (1893) pp. 140-7. 
