336 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
The author gives the results of his observations on the habit of the 
zoarium at different seasons, on regeneration, and on the mode of 
branching of the different species. At Plymouth the dominant species 
is C. ramosa , which is particularly fond of growing on stones. G. eburnea , 
which is also common at Plymouth, is always found on red seaweeds or 
on Sertularia. 
Marine Polyzoa* — The Pev. T. Hincks, in continuation of his 
contributions to a General History of Marine Polyzoa, describes some, 
chiefly South African, and with this concludes the first series of the 
“Contributions,” so far as the descriptive portion is concerned. Flustra 
nobilis sp. n. is a handsome species, in which the zooecia are of unusual 
size ; when they are furnished with forked lateral spines their appear- 
ance is very picturesque. The genus Adeonella cannot be separated 
from Adeona. In Mucronella aviculifera sp. n. the avicularia are not 
only profusely present, but some are large and spatulate, while most are 
minute in size and mounted on the top of a calcareous column or erect 
spine-like process. 
y- Brachiopoda. 
Development of Brachiopoda.f — Mr. C. E. Beecher points out that, 
so far as he has studied them, all Brachiopods have a common form of 
embryonic shell which may be termed the protegulum. It is semicircular 
or semi-elliptical in outline, and has no hinge area. The modifications 
exhibited appear to be due to accelerated growth, by which characters 
primarily neologic become so advanced in the development of the 
individual as to be finally impressed upon the embryonic shell. The 
structure of the protegulum has been described as corneous and imper- 
forate. Kuiorgina seems to preserve throughout its development the main 
features of the protegulum. The greatest departure from the normal is 
exhibited in the most variable and specialized valve, the pedicle valve. 
Variation is also to be seen in the length and direction of the 
pedicle and in the position and structure of the pedicle opening. A 
long pedicle accompanies elongate shells with short hinges, while a 
short pedicle causes extended hinge-growth when the plane of the valves 
is ascending and vertical, but a discinoid form when the plane of the 
valves is horizontal. 
The author proposes to divide the Brachiopoda into the Atremata, 
Neotremata, Protremata, and Telotremata. 
Arthropoda. 
Striated Muscles of Arthropoda. — Prof. 0. Biitschli and Herr W. 
Schewiakoff have investigated afresh the minute structure of the trans- 
versely striated muscles of Arthropods. The objects of investigation 
was the thoracic muscles of Scolopendra sp. and LitJiobius forficatus , the 
cephalothoracic and chelar muscles of Astacus fluviatilis, and the wing- 
muscles of Lucanus cervus, Hydrophilus piceus, and some other insects. 
Every muscle-cell is found to consist of two different kinds of proto- 
plasm — a contractile or fibrillar substance, which forms the contractile 
* Ann. and Mag. Nat. Hist , vii. (1891) pp. 285-98 (2 pis.). 
f Amer. Journ. Sci., xli. (1891) pp. 313-57 (] pi ). 
% Biol. Centralbl.. xi. (1891) pp. 33-9. 
