420 
W. N. F. AVOODLAXF. 
over small areas of the single squamous layer.) The duct 
to the exterior is composed of cells similar to those of the 
gland proper, save that they lack the striated border. There 
is as yet no dilatation to form a bladder. 
Remarks on the Maxillary Gland of Squilla com- 
pared with the Excretory Leg Glands of other 
Crustacea and Arthropod a. . 
If we compare the maxillary glands of Squilla with those 
of the Isopoda (described by Rogenhofer [21]) it is at once 
evident that the former greatly exceed the latter in com- 
plexit}^ of structure, and in fact the maxillary glands of the 
adult Bopyrus, Porcellio, and even Ligia are almost exactly 
comparable, both as regards general form and histology, with 
the early stage of development of the maxillary gland found 
in the 12 mm. larva of Squilla. In Asellus aquaticus, on 
‘the other hand, the kidne}^ region of the gland has, according 
to Rogenhofei’, become much lengthened and convoluted and 
therefore moi-e similar to the maxillary gland of Branchipus 
(Claus [6j) or the antennal glands of Gammarus (Vejdovsky [22] 
and Mysis (Grobben [101). In connection with the antennal 
and maxillary glands of Malacostraca generally it appears 
that the kidney part of the gland is able to undergo compli- 
cation in two different ways : (1) It may either elongate and 
become greatly convoluted (Asellus, Gammarus, Mysis), or 
(2) it may swell and its wall become invaginated by inward 
extensions of the external hasmoccele. As examples of the 
latter method may be mentioned the maxillary gland of 
Squilla and the antennal glands of Cancer (Pearson [18]), 
Homarus (AVaite [23]), Palmmonetes (Allen [1]), etc. I should 
like here to record mv suspicion that many descriptions (e.g. 
AVaite’s description of the antennal gland of Homarus ([23]) 
and AA^eldon’s description of the kidney reg’ion of certain other 
Decapods [21]) of the structure of the kidney region of the 
antennal gland in different genera of Malacostraca commit the 
error of describing as an elongated convoluted duct what should 
