No. 416.] THE TEXAN KQGENENIA. 623 
The muscles of Koenenia are decidedly striated, like those 
of insects. They represent a condition of musculature which 
would be expected in so small and primitive an animal. Worthy 
of note are the two pairs of simple dorsal and ventral muscles 
of the abdomen and thorax. Other important muscles are those 
running from the roof and side of the thorax to the chelicere. 
The muscles of the appendages need not be described, with 
the exception of those extending from the side of the thorax to 
be inserted on the thoracic appendages. These muscles arise 
on the sides of the thorax, opposite to their corresponding legs, 
and, crossing over just above the suboesophageal ganglion, 
become inserted on their proximal joints. The only other 
muscles that need to be mentioned aré the primitive dorso- 
ventral muscles of the thorax and abdomen. These are 
decidedly a very striking feature in the abdomens of 
arachnids. 
Nervous System. — One of the most singular things about 
Koenenia is its large proportion of concentrated nervous sub- 
stance. The concentration of the ganglia is almost equal to 
that of the Araneidz. In this respect Koenenia is even more 
specialized than Thelyphonus. There seems to be no reduc- 
tion of nervous element here due to the absence of eyes, but, 
like all primitive types, it retains its cephalothoracic ganglia 
unmodified. The brain and subcesophageal ganglion unite to 
form one large mass perforated by the small cesophagus. The 
brain is enormous, occupying the entire dorsal portion of 
the head above the level of the cesophagus. It innervates 
the median and lateral sense organs, the labrum, and cheli- 
cere, The subcesophageal ganglion covers the entire floor of 
the head and thorax, and shows in section swellings corre- 
sponding to each of the five pairs of appendages. With a 
slight constriction at the waist, the subcesophageal ganglion 
connects with a single abdominal ganglion which is situated 
in segments two and three, dorsal to the reproductive orifice. 
From this ganglion, nerves run to all parts of the abdomen and 
tail. In its nervous system Koenenia is thus very unlike the 
Scorpionidea and differs from Thelyphonus in the relative size 
of the cephalothoracic ganglion and in the situation of the 
