1881. ] 3 Zoblogy. 743 
The infinite variety of the forms is, however, the most astonish- 
ing point, transitional types abound, and groups hitherto regarded 
as very distinct are now linked by intermediate forms. As exam- 
ples, the author cites the Paguridz, generally placed among the 
nomura, and which have as yet had no link uniting them to the 
Macrura; now there is Pylocheles agassizii, in which the abdomen 
is not soft and asymmetrical, but is formed of solid regular rings, 
and terminated by swimmerets. This creature lives in holes, 
which it closes by means of its claws. Mixtopagurus has the ab- 
domen more developed on the right than on the left side, and di- 
vided into seven segments, of which the last two are alone large 
and hard. There are some curious adaptive modifications: Eupa- 
gurus discoidalis, which lives in the tubular shells of Dentalium, 
has one of its claws spherical. Xylopagurus lives in holes in 
wood, and has its abdomen converted into an operculum for cov- 
ering one of the two holes of its retreat. Similar connecting links 
were found between the Dromidz and the Homolidz, and on the 
whole the author concludes that submarine explorations will aid 
paleontological investigations in gradually filling up the lacune 
how existing in zodlogical systems. 
Tue Musk Surep.—lIn Dr. Bessel’s account of the North Pole 
expedition published in German, and noticed in Nature, valuable 
accounts of this animal are given. None of those killed by the 
members of the expedition had a very marked musk smell. The 
author is uncertain whether this peculiarity is to be attributed to 
the very high latitude in which they were obtained, or to their 
having been killed out of the breeding season. No difficulty was 
found in distinguishing the tracks of these animals from those of 
reindeer, although some former observers have not found this 
easy. In all the herds there are from ten to twenty cows to one 
bull. Their whine is somewhat like the snorting of the walrus, 
and never resembles in the least the cry of the goat or the sheep. 
When danger approaches they never give signal with their voice, 
but only by stamping or striking their neighbor with their horns. 
They have dire combats with bears sometimes, and often come 
off victors, ; 
Zootocicar Norrs—The organization of an Echiurus-like 
Sipunculoid worm (Thalassema mabu Greef), has been studie 
ey are arranged in two or three rows on each side of the 
mouth cavity, or externally on the proboscis of Pterotrachea. 
They are little papilla with internal sense-cells situated next to 
the termination of the nervous fibrilla, while externally they each 
carry a long sensitive hair, and the different sensitive hairs of these 
cells traverse the canal of the cuticular layer, and arrive at the 
