114 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
sand ; and (3) tlie region of horny corals and sponges. About 40 new 
species of Antliozoa ( Alcyonium , Sarcophylon , &c.) were found. Note- 
worthy were a number of Gastropods parasitic on Echinoderms. The 
second region yielded a little lancelet. A small Gephyrean was found 
as a commensal of a small single coral. 
The author has a good deal to say in regard to the wondrous colours 
of the “ sea-gardens ” — protective colours, warning colours, mimetic 
colours, sexual colours — originating in the course of metabolism, influ- 
enced by environment, and fixed by selection. 
The theory of the polar origin of faunas is rejected on various 
grounds ; in fact, too simple generalisations are fallacious ; distribution 
is a function of very numerous factors. A discussion of the Malayan 
distribution, e.g. of such features as Wallace’s line, is full of interesting 
material. 
But a summary of such a large work is obviously out of the question 
here. We must be content to congratulate the author on his magnificent 
and important work. 
Tunicata. 
Development of Anterior Portion of Salpa.* — Signor F. Todaro 
divides the development of Salpa ( S . africana maxima) into two periods. 
The first period embraces the formation of the gut, the endoderm of 
which, completely closed, is surrounded by ectoderm. Between these 
two membranes, separated by mesenchyme, there arise the peribranchial 
sac, the cerebral vesicle, the pericardial sac, and in the chain-embryo 
some traces of reproductive organs. The second period is initiated by 
the formation of the primitive buccal cavity, and includes the differen- 
tiation of the organs mentioned above into their adult state. 
The primitive buccal cavity or paleeostome shows palingenetic sim- 
plicity in its origin. In its first stage it is an open ectodermic invagina- 
tion ; in a second stage the external aperture is shut, and the palasostome 
is a closed sac ; thereafter, when the brain shows three vesicles, a 
communication between buccal sac and gut is effected ; an opening is 
formed between the anterior cerebral vesicle and a dorsal diverticulum 
of the paleeostome — the anterior neurenteric canal of Kupffer, the 
“ palaeoneural canal ” of Todaro ; much later, a secondary ectodermic 
invagination forms the stomedseum, or neostome, or definitive mouth. 
The communication between cerebral cavity and palseostome is 
subsequently lost, the diverticulum of the latter becoming a ciliated pit, 
the palseoneural canal becoming a blind infundibular canal. From the 
infundibular vesicle are formed two hypophysial vesicles, while two 
ectodermic diverticula give rise to the tubular part of the hypophysial 
gland. Thus ike paired hypophysial or subneural gland of Salpa has a 
double origin — from the cerebral infundibulum and from the ectoderm 
of the palaeostome. The last thing to be formed from the paheostome is 
the peripharyngeal groove. 
Cerebral ganglia, olfactory ganglia, eyes, and peripheral nerves are 
derived from a mass of indifferent cells in the cerebral region. The 
paired olfactory ganglia are first mapped out and separated from the 
cerebral rudiment ; the originally small cells become large, and two 
nerves are given off to the ciliated pit. 
* At ti R. Accad. Lincei Bend., vi. (1897) pp. 51-61 (1 fig.) 
