The order _EURYPTERIDA_ comprises an extinct group of Crustacea closely allied to the modern King-crab (_Limulus_). The body was covered with a thin chitinous skeleton, ornamented with regular scale-like markings. This group is represented in Victorian rocks by the remains of _Pterygotus_ ("Sea-scorpions"), animals which often attained a length of six feet. _Pterygotus_ (see Fig. 121 A) had the fore part of the body fused, forming the cephalo-thorax, which was furnished with anterior, marginal facetted eyes and central ocelli or smaller simple ones. To the ventral surface of the body were attached six pairs of appendages. The first pair are modified antennae with pincer-like terminations, used for prehensile purposes. Then come four pairs of slender walking feet. The sixth pair of appendages is in the form of powerful swimming feet or paddles, at the bases of which are the comb-like jaws. The abdomen consists of thirteen joints, the last of which, the telson, is spatulate and posteriorly pointed. Fragments of a tolerably large species of _Pterygotus_ occur in the Silurian shales of South Yarra, Melbourne, Victoria. It was probably about 18 inches in length when complete. Of this form, known as _P. australis_ (Fig. 121 B), portions of the chelate (clawed) appendages, and parts of the abdominal segments have been found from time to time, but no complete fossil has yet been discovered. [Illustration: =Fig. 121--SILURIAN EURYPTERIDS.= A--Pterygotus osiliensis, Schmidt. I. of Oesel. (_After Schmidt_) B--Pterygotus australis, McCoy. Part of a body-segment. Silurian (Melb.) Victoria ] =Jurassic Insects.--= Of the group of the _INSECTA_, the Ipswich Coal measures (Jurassic) of Queensland have yielded an interesting buprestid beetle (_Mesostigmodera_), whilst beds of the same age in New South Wales contain the remains of a probable _Cicada_, associated with leaves of the fern _Taeniopteris_. =Lower Cretaceous Dragon-fly.--= From the Lower Cretaceous of the Flinders River district, Queensland, there has been obtained a fossil dragon-fly, _Aeschna flindersensis_ (Fig. 120 D). =Cainozoic Insects.--= Certain Cainozoic beds of New South Wales, of the age of the Deep-leads of Victoria, and probably equivalent to the Kalimnan terrestrial series, contain a species of _Cydnus_, a bug-like insect belonging to the order Rhynchota; and there are in the same series a Midge (_Chironomus_), a Day-fly (_Ephemera_, Fig. 120 E) and several beetles (? _Lagria_, _Palaeolycus_, _Cyphon_ and _Oxytelus_). The occurrence of these insects of the Deep-leads helps to complete the landscape picture of those far-off Lower Pliocene times, when the old river systems brought down large contributions of vegetable waste from higher lands, in the form of twigs with leaves and fruits; with occasional evidences of the rich and varied fauna of insect life which was especially promoted in the damp and vegetative areas of the lower lands.