WILLIAMS: HABITS OF SCUTIGERELLA. 
465 
its own rudimentary coxal gland as well. He further considers the 
pair of cerei, which carry the ducts of the spinning glands, as homo¬ 
logous with a pair of legs. The paired stylets by the cerei, considered 
sensory by all authors, would then probably be the modified parapods 
of the segment on which the cerei represented the legs. 
Hansen (’ 03 ) in his paper adds a description of a peculiar type of 
sense organ, the striped sense organ, of which he finds one or more 
examples on the terminal segments of the antennae and which are also 
found, but less abundantly, on other antennal segments. “An organ 
of this kind consists of a stalk, which is either short or rather long, 
often gradually increasing in thickness outward and from its end 
originate four fine branches which are slightly convex outward, sub¬ 
parallel or slightly diverging and certainly always united by a very 
thin clear membrane/’ These organs are exceedingly small. He 
used a magnification of 600 diameters in their study. Hansen also 
described the mouthparts in the following order: (1) two-jointed 
mandibles, (2) maxillae with palps, (3) labium, (4) maxillulae (para- 
glossae of Grassi) which he considers homologous with the first maxil¬ 
lae in Crustacea and lower insects. 
Carpenter (’ 05 ) emphasizes the presence of three pairs of mouthparts 
behind the mandibles in the Symphyla. His description of the mouth- 
parts differs in its order from that of Hansen. He describes (1) man¬ 
dibles, (2) maxillulae, (3) 1st maxillae, (4) labium. 
He finds in the Symphyla the same number of trunk segments as 
in insects and the same total number of segments (22) in this group 
of the Symphyla as in the widely separated arthropod forms, the lobster, 
the cockroach, and the scorpion. 
Distribution. 
Till 1903 there had been but four accepted species of the Symphyla 
described in the 138 years that had elapsed since Scopoli described the 
form now known as Scutigerella nivea. These were known only from 
Europe and the United States of America. 
The paper by Hansen (’ 03 ) on the genera and species of Symphyla 
describes a total of twenty-four species all but five of which are new. 
Twelve of these belong to the genus Scutigerella and twelve to the 
genus Scolopendrella. 
These animals have thus far been found in Europe, Algeria, Cape 
