ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
485 
e. Crustacea. 
Respiratory Organs of Oniscidse.* * * § — Mr. J. Stoller has subjected 
these organs to a detailed histological examination in several genera, 
with special reference to the corpora alba found on the outer gills in 
Porcellio and Armadillidium. In these genera some or all of the outer 
gills bear white structures which careful examination shows to be tree- 
like organs having a single opening to the exterior, and formed by an 
inturning of chitin. These contain air, and are in some respects com- 
parable to the tracheae of insects. The author is of opinion that their 
function is to enable the Isopods to breathe dry air, while the inner 
gills, which are without trees, can serve as respiratory organs only 
when the air is moist. As the terrestrial Isopods have arisen from 
aquatic ancestors, those forms in which all five pairs of outer gills bear 
trees must be considered more specialised than those in which there are 
two pairs of these organs only. In Lygidium hypnorum , which lives 
only in very moist situations, no trees or similar structures are present 
on the outer gills. In Oniscus murarius the trees are again absent, but 
the outer gills contain an elaborate series of chambers whose function 
the author believes to be similar to that of the trees, that is, they enable 
the animal to breathe in ordinary atmospheric air. 
Winter Egg- of Leydigia acanthocercoides Fisher, f — Mr. D. J. 
Scourfield describes for the first time the winter egg of this rare water- 
flea. The egg is enclosed in a proto-ephippium of complex structure, 
which is formed from a relatively small portion of the shell of the 
mother, and is provided with large hooks whose function is probably to 
ensure the distribution of the egg. Between the egg and the proto- 
ephippium there is a mass of spongy tissue. The egg-case, as a whole, 
differs from the true ephippium of Daphnids in the absence of surface 
sculpture, but in its general structure forms a link between the egg- 
cases of this family and those of other Lynceids. 
Annulata. 
Morrell’s G-lands in the Lumbricidse.J — M. Edouard de Ribaucourt 
finds that in Lumbricus there are four pairs of Morren’s glands, and not 
three as hitherto supposed. Of these the minute newly discovered 
posterior one is the oldest, the anterior and the two median ones are 
secondary differentiations. In Allolobophora hermanni Michaelsen the 
four pairs of glands are entirely absent. Between this condition and 
that seen in Lumbricus Jierculeus it is possible to trace a complete series 
of stages, illustrating the gradual development of the condition where 
four pairs of glands are present. 
Observations on 01igochaetes.§ — Dr. W. Michaelsen has investi- 
gated some fragments of a worm in the Hamburg Museum labelled 
Georyctes menkei Schlotthauber. He finds that its true name should 
be Phreoryctes gordioides Hartmann, a species with a very extensive 
synonymy. The author finds that the first segment is rudimentary, a 
* Bibliotheca Zoologica, xxv. (1899) pp. 1-31 (2 pis.). 
t Journ. Quekett Micr. Club, vii. (1899) pp. 171-9. 
X Comptes Kendus, cxxviii. (1899; pp. 1528-30. 
§ Zool. Jahrb., xii. (1899) pp. 105-44 (2 fi^s.). 
