icith Modern Representatives. 391 



PI. XIV, rig. 4, and text-fig.; also of Palceocaris Burnettii, H. "Wood- 

 ward, sp, nov., p. 533, PI. XIY, Pig. 3«, h, Coal-measures, Irwell. 



3. Palceocaris typus, Meek & Worthen, 1865 (Fig. 8) (Proc. 

 Acad. Nat. Sci., Philad., and Keport Geol. Surv., Illinois, 1868), was 

 obtained by its original describers from the Coal-measures of Grundy 

 Co., Illinois. It was afterwards redescribed by Packard in 1866.^ 

 The head is represented as truncated in front and is quite small ; 

 the body uniformly segmented ; there are seven distinct thoracic 

 segments, but over these there is no backward extension of the head- 

 shield ; the first five abdominal segments have downwardly projecting 

 pleurae ; the sixth segment is elongated and cylindrical in form. 

 The tail-fan and telson are similar to those of the Palgemonidae, or 

 of a Mysis-like shrimp. The eyes are not seen in the fossil, but the 

 antennules have a stout three-jointed peduncle strongly developed, and 

 each carries a pair of flagella, the outer one longer than the other. The 

 antennae carry a broad scale, or exopodite, and a long multi-articulate 

 flagellum. The thoracic appendages (as represented in Packard's 

 restoration) have each a three- or four-jointed exopodite borne upon 

 a slender walking- or swimming-limb, the distal extremity of which 

 latter is not shown. Each of the five (abdominal) segments which 

 follow carries a pair of pleopods of the usual slender, setose, multi- 

 articulate form. 



Fig. 8. — Palceocaris typus, M.. kW. Coal-measures: Illinois. After Dr. Packard's 

 figure. 



Living analogues of Coal-Measure Schtzopods. — In the examination of 

 fossil forms from the older rocks, we are seldom so fortunate as to find 

 a living analogue by which to interpret these too often rare and im- 

 perfect organic remains ; nevertheless, amongst the discoveries made 

 in Australasia in recent years, two forms have attracted considerable 

 attention, as indicating very early and primitive types of Crustacea, 

 and throwing an important light on several remarkable Coal-measure 

 Crustaceans, previously without any very near existing representative. 



1 . The first of these living Schizopod Crustaceans was noticed, under 

 the name of Anaspides tasmanice, by Mr. G. M. Thomson, of Dunedin, 

 in 1894.- Its describer discovered it it in a freshwater pool, at an 



' Mem. Acad. Nat. Sci., Washington, vol. iii (2), 1886. Abstract in Amer. 

 Naturalist, vol. xix (1885), pp. 790-2. 



^ Trans. Linn. Soc. Lond., Zoology (2), vol. vi (1894), p. 3. A preliminary- 

 account, without figures, has been previously published in Proc. Eoy. Soc, 

 Tasmania, 1892. 



