ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
313 
Balanus. He thinks that it is tolerably certain that the antennae of 
the Nauplius become definitely lost with the moult which results in 
the production of the Cypris-stage. The biramous mandibles in the 
Nauplius become reduced at the same time to the small mandibles, the 
ramus of which is probably preserved in the form of a small palp. 
The first pair of maxillae arise behind the mandibles, and at a later 
date, as a small pair of foliaceous appendages. The second pair of 
maxillae arise still later, just in front of the first pair of thoracic legs. 
In the fate of the mandibles of the Nauplius and in the constitution 
of the head of the adult, the Cirripedia may be seen to conform to what 
is recognised as typical among other Crustacea. 
Structure and Appendages of Trinucleus. * — Mr. C. E. Beecher 
has a note on some new facts regarding the structure and appendages of 
this ancient Trilobite. With regard to the so-called eye-line, which 
occurs in many early Trilobite genera, he points out that at least four- 
fifths of the Cambrian forms preserve this feature, which was almost 
entirely eliminated before Devonian time. It is evidently a larval 
character in Trilobites, as shown from its geological history and the 
ontogeny of Trinucleus. It is surmised from the direction of the optic 
nerve in Limulus , and its relation to the surface features of the cephalo- 
thorax, that the eye-line probably represents the course of that nerve, 
and that it is of much less morphological importance than the different 
types of visual organs. Three specimens have now been observed, 
which show the nature of the appendages of Trinucleus. Their characters 
appear to indicate an animal of burrowing habit, which probably lived 
in the soft mud on the sea bottom, much after the fashion of the 
modern Limulus. Jn addition to its limuloid form, the absence of eyes 
seems to favour this assumption, as does the fact that many specimens 
have been found preserving the cast of the alimentary canal, for this is 
a proof that the animal gorged itself with mud like many other sea- 
bottom animals. 
Annulata. 
Function of Amcebocytes in Polychaeta.f — M. E. G. Racovitza has 
studied Leiocephalus leiopygos by injecting directly into the general 
cavity sepia ink. In about a fortnight the rosy colour of the anterior 
segments of these worms became blackened, and sections showed that 
this coloration was due to the presence of granules of ink in the 
epidermis. These granules were for the most part contained in longi- 
tudinal cells, which were undoubtedly undergoing degeneration. The 
deposit of the black granules in the epidermis is clearly the result of the 
diapsedesis of the amoebocytes. The transport of excretory granules of 
these cells has been already demonstrated in the most diverse groups, 
and numerous works confirm the beautiful theory of Eisig on the 
excretory origin of the coloured pigments of animals. The author 
concludes that amoebocytes do not merely serve to deposit excretory 
pigment in the epidermis, but that on occasion they will withdraw and 
digest reserve substances which have accumulated in the organism. 
* Amer. Journ. Sci., xlix. (1895) pp. 807-11 (1 pi.). 
t Comptes Kendus, cxx. (1895) pp. 464-7. 
