414 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Cyclopidse and Calanidse of Michigan Lakes.* * * § — Prof. C. D. Marsh 
has made a biological examination of the lakes of Michigan. He finds* 
that the Copepod fauna of the Michigan Lakes is richer than those of 
the Continent of Europe ; whereas Zacharias found seven species in the 
Lake of Plon, in Lake Michigan there are nine, in Round Lake eleven, 
and in Lake St. Clair sixteen. One new species only has been observed, 
Diaptomus reigJiardi. The species of this genus are in some cases 
quite limited in their distribution, and appear to be more susceptible to 
the influences of the environment than are species of Cyclops. Very 
little indeed is known of the life-histories of the species of Diaptomus, 
and it is possible that a more complete knowledge may lead to a reduc- 
tion in the number of species. So far, however, as the author can see, 
all the forms described vary within comparatively narrow limits, and 
there is no evidence to lead us to question the separation of the forms. 
Anatomy of Tetraclita porosa.f — M. A. Gruvel finds that the 
structure of this Cirripede agrees with the normal structure of its 
group, but the test appears to form an intermediate stage between that 
of Chthausalus and Balanus. His paper contains merely a detailed 
account of his observations. 
Respiration of Trilobites.f — Hr. C. E. Beecher is reported as remark- 
ing on the probable method of respiration in Triarthrus in the following 
terms: — No traces of any special organs for the purpose have been found 
in this genus, and their former existence is very doubtful, especially in 
view of the perfection of details preserved in various parts of the animal ; 
the delicacy of the appendages and vential membrane of Trilobites and 
their rarity of preservation are sufficient demonstration that these portions 
of the outer integument were of extreme thinness, and therefore perfectly 
capable of performing the function of respiration. Similar conditions 
occur in most of the lower Crustacea. 
Annulata. 
Polychaeta of Dinard. § — The Baron de St. Joseph has published an 
appendix to the four memoirs which he has already published on these 
worms. The most interesting part of it is, perhaps, that in which he 
discusses their geographical and bathymetrical distribution. In the last 
twelve years he has observed on the coasts of Hinard 207 species, 53 of 
which, or about a quarter, are new ; 50 species inhabit the shore only, 
while another 50 inhabit both the shore and the bottom of the sea. 
The depths from 4 to 27 metres below low-water mark are occupied by 
103 species. So far as we know at present, 34 of the species are confined 
to the coasts of Dinard, and of the 20 other new species established by 
him, 3 have been found in the English Channel, 7 in the Straits of 
Dover, 6 in the Atlantic, 1 in the Channel and the Atlantic, 1 in the 
Straits of Dover, the Channel, and the Mediterranean. From the analysis 
which he makes he finds that 22 species which are found at Dinard are 
found in the Glacial Arctic Ocean, 02 in the North 8ea, 124 in the 
* Bull. Michigan Fish Commission, No. 5 (1895) 24 pp. (9 pis.), 
t Comptes Rendus, cxxii. (1896) pp. 205-7. 
j Amer. Journ. Sci., i. (1896) pp. 251-5 (1 pi.). 
§ Ann. Sci. Nat., xx. (1895) pp. 185-272 (3 pis.). 
