ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
563 
first segment, the great labrum with antennae attached at the sides, 
the “ wandering ” of the eyes, the pores which point to the probable 
presence of water-sacs, the head with a varying and progressively 
increasing number of segments, and the essentially lobate and phyllo- 
podan type of limbs, serve, with other characters, to connect the Trilo- 
bites with Apus. 
This relationship must not, however, be supposed to be direct ; Apus 
lies in the direct line upwards from the original Annelidan ancestor to 
the modern Crustacea, while the Trilobites branched off from the line 
as forms specialized for creeping under the protection of a hard imbri- 
cated carapace. Two alternative lines of descent with modification are 
sketched, and it is urged that the repetition of the head-shield as pleurae 
along the trunk-segments seems to be the specialization which charac- 
terizes the Trilobites. 
Mr. Bernard thinks that these organisms, studied in the light of 
recent and especially American investigations, give important evidence 
as to the origin of the Crustacea. Stripped of their pleurae and of the 
expansion of the head-shield the early Trilobites (e. g. Olenellus ) are 
seen to be long, segmented animals tapering at the posterior end. The 
members of the group, as a whole, may be defined as fixed specialized 
stages in the evolution of the Crustacea from an Annelidan ancestor, 
which bent its mouth round ventrally so as to use its parapodia as jaws. 
In the discussion which followed the reading of this paper Prof. 
G. B. Howes * said some severe things of the “ Limulus-an- Arachnid ” 
theory. 
e. Crustacea. 
Crustacea of Malay Archipelago.f — Dr. L. Zehntner gives a list of 
the Malacostraca and Cirripedia collected by MM. Bedot and Pictet. 
It contains the names of ninety-four species, twenty-one of which are 
new ; the large number is partly due to old Madreporae and Tubiporae 
having been broken open, when a very rich and interesting fauna of 
small forms was found. The new genus SpJiserocarcinus is formed for 
S. Bedoti sp. n. ; it is closely allied to Lissocarcinus and is founded on a 
single, female, specimen. 
Histology of Nervous System of Embryonic Lobster.!— Mr. E. J. 
Allen has studied the nervous system of late embryos of Homcirus vulgaris 
by a modification of Ehrlich’s methylen-blue method. The nerve-elements 
which stained may be divided into three groups. 
(1) Elements of which both cell and fibre lie entirely in the gang- 
lionic chain ; these must be supposed to co-ordinate the action of its 
various parts. 
(2 ) Elements which consist of a ganglion cell in the cord and a fibre 
which runs out at a lateral nerve-root ; some, perhaps all, of these 
elements are connected with muscles, and are motor. 
(3) Elements which consist of a cell lying outside the central 
ganglionic chain, and a fibre running from it to a ganglion ; these must 
be regarded as sensory elements. 
The co-ordinating elements are of four kinds : — (A) Elements made 
* Tom. cit., p. 433. f Ptev. Suisse Zool., ii. (1894) pp. 135-214 (3 pl 3 .). 
+ Proc. Koy. Soc. Loud., lv. (1891) pp. 407-14 (1 fig.). 
