Ma bya CRUSTACEA—SYNCARIDA CHAP. 
The division PERACARIDA, including the Eucopiidae, Lopho- 
gastridae, and Mysidae (= Mysidacea), the Cumacea, Isopoda, 
and Amphipoda, is characterised by the fact that when a carapace 
is present it leaves at least four of the thoracic segments free 
and uncoalesced: by the presence of a brood-pouch formed from 
the oostegites on the thoracic limbs of the female: by the 
elongated heart: by the few and simple hepatic caeca: by the 
filiform spermatozoa: and by the direct method of development 
without a complicated larval metamorphosis. The biting face of 
the mandible has a movable joint, the “ lacinia mobilis.” 
The division Eucaripa, on the other hand, including the 
Euphausiidae and the Decapoda, shows the converse of these 
characters. The carapace coalesces with all the thoracic seg- 
ments, there is never a brood-pouch formed from oostegites, the 
hepatic caeca are much ramified, the heart is short, the spermato- 
zoa are spherical with radiating pseudopodia, the development is 
indirect with a complicated metamorphosis, and the mandible is 
without a lacinia mobilis. 
Corresponding divisions are made by Calman to receive the 
other Malacostraca, namely, the PHyLLocaripA for Nebalia, the 
SYNCARIDA for Anaspides, and the HopnLocaripa for the 
Stomatopoda or Squillidae. 
The important array of characters which separates the 
Euphausiidae from the other Schizopods and unites them with 
the Decapoda can no longer be neglected, and the consideration of 
Anaspides and its allies will further emphasise the extreme 
difficulty of retaining the Schizopoda as a natural group. In 
the sequel Calman’s proposed scheme will be adopted. 
DIVISION 1. SYNCARIDA. 
There is no carapace, and all the eight thoracic segments may 
be free and distinct. Eyes may be pedunculate or sessile. The 
mandible is without a lacinia mobilis. There is no brood-pouch, 
the eggs being deposited and hidden after fertilisation. The 
spermatozoa are filiform, the hepatic caeca very numerous, and 
the heart tubular and elongated, with ostia only in one place in 
1 The lacinia mobilis is a movable tooth-like structure jointed on to the biting 
face of the mandible. 
