ON THE ANASPIDACEA, LIVING AND FOSSIL. D090 
originally simple structure and by the addition of new organs 
to comparatively undifferentiated organisms, but rather by 
the segregation and separation of characters originally com- 
bined in one ancestral form into the various streams of 
descent which have emerged from it—if this opinion might 
at any time be adopted and sustained, it would influence our 
attitude to the philosophy of evolution as profoundly as any 
conceptions deduced from the experimental study of living 
organisms, without reference to the history which they have 
passed through. 
6. Systematic Part. 
The Anaspidacea, living and fossil, are placed in a sepa- 
rate division of the Humalacostraca. Thus: 
Division Syncarida (Packard 5 and 6, Calman 9). 
A carapace is absent. The thoracic somites are either all 
distinct, or the anterior one may be fused to the head. ‘I'he 
eyes are pedunculated or sessile. An otocyst is present on 
the basal joint of the antennules. he antennal protopodite 
consists of two segments. ‘lhe mandible is without a lacinia 
mobilis. ‘The thoracic limbs consist typically of eight seg~ 
ments, and the ‘‘ knee-joint”’ is between the fifth and sixth 
segment. There are no oostegites. A spermatheca is present 
on the last thoracic segment of the female. ‘There is no 
appendix interna on the pleopods. The endopodites of the 
first two pleopods of the male are modified to form copulatory 
styles. The branchiz form a double series of leaf-lke 
plates on all but the last or last two thoracic limbs. The 
heart is elongated and tubular. The alimentary canal is 
furnished with three dorsal diverticula, one at the junc- 
tion of the stomodzum and mid-gut, one in the middle of 
the mid-gut, and one at the junction of the mid-gut and 
proctodeum. The hepatic cxeca are numerous, elongated 
and unbranched, and without glandular ridges. The 
