145 
»Bauchtaster" of the Gamasidae as a labium, maintains consequently 
that only the maxillae and the labrum take part in the etablish- 
ment of the pharyngeal tube. This last theory seems to me the 
most naturål, though I admit that still more facts — chiefly em- 
bryological ones — are necessary to settle the question. definitively. 
Within: the: pseudocapitulum, and forming the ceiling -of the 
pharyngeal tube, the labrum is found. I call this organ labrum, 
following the terminology of Dr. H. J. Hansen ånd. W, Sørensen, 
though most acarologs have used other names (rostrum, lingula and 
epipharyna). The pharyngeal tube is established by thé coalescence 
of the labrum and. the maxillae, and is penetrated by the pharynx, 
which tåkes its origin where the labrum and the måxillåe coalésce 
with each other. The antennae are articulated beneath the rostrum 
and above the labrum. 
Shape in" Eucarus. The pseudocapitulum (pl. IV fig. 4 & 5) 
is articulated to the ,,head” in a large cavity, the position of which 
is obliquely downwards ånd båckwards, because the front part of the 
heåd projects as a semi-roof over its base, and the sides of the 
cavity being directed båckwards and downwards. The articulation 
membrane permits movements in several directions chiefly up- and 
downwards. As in the other Acari the pseudocapitulum is composed. 
of the rostrum, the labrum and the coalesced maxillae, and consists 
of two'tubes, an upper, imperfect one including the attende, and 
a lower one, the pharyngeal one. 
a. Rostrum. The ,,rostrum" (pl: IV fig. 4 & 5'r. pl. VI fig. 1») 
only covers the base of. the antennae and is itself covered by the 
front pårt of the head, on account of which it is thin ånd mem- 
branous. This organ which is identical with the ,,rostrum" in other 
Acari is by a fine impressed line divided into a right and a left 
part and is slightly granular. As will be seen in the longitudinal 
section (pl. VI fig. 1) it may be regarded as the dorsal part of a 
sheath formed by the invaginated antennae. It is coalescéd with 
the base of the backwardly directed projection of the' maxillae, and 
as it is so little developed the greater distal part SA the "dress tube 
Vidensk. Meddel. fra den naturh. Foren. 1904. 
