On the markings of the Carapazr of Crabs. 97 
: and also 1M apd 2M. Next, the posterior of the medial areolets 
becomes obsolete, and at the same time 5L, 6L disappear, or are 
indicated only by a slight undulation along the space that ordi- 
narily separates them. The extra-medial may be only circum- 
scribed anteriorly, and the slender elongation of the interno-me- 
dial is all that appears of that areolet ; next, the remaining antero- 
lateral areolets may disappear with the frontal, and the surface 
is then quite smooth. 11, is sometimes indistinct when the other 
areolets are prominent, though usually it accompanies them. 
hen 4L, 5L, 6L become indistinct, the transverse depression 
then prominent instead of passing behind them bends more forward 
along 3M, and passes anterior to them, and so makes a different 
2 subdivision of the carapax in its general aspect and character. In 
another variety, the prominent transverse depression passes ap- 
terior to 5L, but not anterior to 4L, (which may be obsolete, ) and 
has nearly a straight course across the carapax. 
In the subdivision of the areolets, the first that partake of it 
are 2M, 5L, and 3M. A commencement of this subdivision of 
2M (the extra-medial) is very common, and when completed it 
divides it into two parts longitudinally. This is an important 
specific character and though hitherto unmentioned in descrip- 
tions, it is easily described when a proper notation is adopted. 5L 
also subdivides from above downward or rather obliquely inward. 
3M subdivides at times into 3 parts as shown in figure 2 which in- 
cludes also 4M. Figure 3 represents another form of this areolet 
eS eee a ey ct anh = | 
“ - - ag f 
Seay er 
some smaller; and the post-medial includes 2 tango eat’ Saree 
smaller tubercles. When the subdivisions are not carried as far, 
a portion may be separated anteriorly from each half of 2M, while 
me rest remains entire. ‘ 
oat is common for 1R to have a tubercle or two on its surface 
e same transverse line with the tooth, 
ol, XI, No, 31—Jan., 1851. 18 
