61 Orust, 
CRUSTACEA. 
duplicature of the integument of the back, and contains the liver and 
ovary, between the outer stronger and the inner membranaceous layer, 
the oviduct opening in the first pair of feet ; the testicles are contained 
in the second-fifth pairs of feet, in which the vasa deferentia are opened; 
the sixth pair of feet are more slender, and have no generative func- 
tions. Both sexes are united in the same individual ; the eggs are fecun- 
dated within the test ; the Nauplius-stage of development with three 
pairs of feet has been observed. L. gerardice, sp. n., is fixed on its back 
to Gerardia (Gorgonia tuherculata, Lam., = Liopathes lamarcJci, M.-Edw.), 
in the Mediterranean, and enveloped by its coenosarc throughout except 
the hiloid aperture ; test 2-4 centimetres long. Lacaze-Duthiers, Arch. 
Z. exper. viii. pp. 537-581, woodcuts ; abstract in J. B. Micr. Soc. (2) i. 
pp. 242 & 243. 
XIPHOSURA. 
A. S. Packard gives an anatomical (chiefly histological) description of 
Limulus polyphemus^ discussing the histology of the intestinal tract, the 
structure of the liver, and the bright red glandular bodies, which he sup- 
poses to be renal in their nature, although apparently lacking an excre- 
tory duct. As regards the structure of the eyes, he confirms in most 
parts the description of the compound eye given by Grenacher [Zool. 
Bee. xvi. Crust, p. 6], and adds the histological description of the ocellus; 
the latter is very simple, exhibiting a repetition of the general structure 
of the individual eyes of the compound organ of vision, but rather more 
rudimentary. The hard parts of the compound eyes of the Trilobites, 
especially Asaphus, here also described, show the closest possible homo- 
logy with those of Limulus ; the ocellus of the Myriapods, on the con- 
trary, is, as a whole, entirely unlike that of Limulus. The author also 
describes the general anatomy, internal structure, and histology of the 
brain and oesophageal and abdominal ganglia ; histologically, the brain 
agrees with that of the higher Crustacea, in having similar large and 
small ganglion -cells, but topographically its internal structure is con- 
structed on a wholly different plan. The paper is concluded by some 
further contributions to the embryology of Limulus, describing the 
blastodermic skin, or serous membrane, the first appearance and develop- 
ment of the nervous system and digestive canal, the origin of the liver, 
the structure of the testes, and the development of the spermatozoa. 
Transverse sections of the whole animal and injections of the arteries are 
represented on the plates.^ The author comes to the conclusion that 
Limulus really belongs to the Crustacea, but forms with the Trilobites, 
a special subclass “ Palceocarida,'' in which there are no true antennae, 
the gnathopods are modified mouth- parts (the last pair possibly represent- 
ing a pair of thoracic feet' , the fore part of the body corresponds to 
the cephalothorax of the Decapoda, the posterior part being truly an 
abdomen, and the spine simply the last body-segment, or ninth abdominal 
arthromere. Anniversary Mem. Bost. Soc. 1880, 45 pp., 7 pis. 
See also anted (p. 6), “ Nervous System and “ Organs of Sense.” 
