Botany and Zoology. 117 
these legs are otherwise like the preceding, though somewhat smaller, 
and it is probable that this habit in the MW. mutica has been overlooked, 
as these animals almost always swim with the posterior legs extended 
like the others, when taken and kept in a jar for examination, and they 
also have them extended when walking. These legs do not resemble 
at all the posterior pair in Porcellana or Galathea. I had examined 
several species before I discovered this habit with regard to the poste- 
tior legs. The animal also throws the fourth pair of legs forward along 
ot over the borders of the carapax, so that the extremity overlies the 
bases of the eyes and the tarsi hang down in front; and at the same 
time the two preceding pair are folded up and lie against the sides of 
the carapax outside of the 4th pair, or the third pair may be thrown 
forward like the 4th. A Sooloo species, and another common off Cape 
rowed forward, 
The other division has the tarsi unguiform, compressed, and spinous 
‘low, the antepenult spine always longest; the fossa of the sternum 
- with flaring borders; the depression of the carapax for the posterior 
legs shallow concave ; the body more flattened above, with. the sides 
More oblique. This division corresponds to Monolepis spinitarsus. 
Besides the preceding, there is another group of Megalopidea, om 
tarsus of the posterior legs is narrow lamellar instead of unguiculate, 
and edged with longish sete somewhat shorter than the tarsus. 
tere is still another ‘group in which the front is horizontal and tri- 
Cuspidate, the inner antenne when retracted being exposed in the in- 
terval between the beak or inner cusp and either outer, lying in view 
as In Plagusia. 
With these explanations we give the characters of the genera. 
Fis Monotsris, Say.—Carapax fronte tricuspidatus sed valde deflexus 
Meoque frons superne visus medio non acutu sed truncatus, Pedes 
't minores, Supe carapacem srepe restantes, sione a ‘ ci- 
Plendos abrupta ; tarsis inermibus, depressis, styliformibus, paris postict 
le 
bs x ic 
non depressis, apice 3—4 setis longiusculis (tarso paulo — ongioribus) 
wee Sterni fossa abdominalis marginibus bene prominens et sub- 
uta.— Monolepis inermis, Say, typus est. 
$ og ; m » ge 
* Mangsria, Dana.—Carapax fronte uti in Monolepi. Pedes 8 
Postici ad basin infra non armati; Sti minores, super carapacem s&pe 
* Journ. Acad. Nat. Sci, Philad,,i, 155. ‘The author is indebted for the privilege 
of examining a speci Sab alhl i to Prof, Lewis R. Gibbes of Charles. 
ton, 8.0." Anotitr related species was obtained by the author inthe East Indies 
