. Geological magazine. somites, exposed to view,united along the median line by a longi-tudinal ridge. The pseudo - appendages, however,have no evidence of any what seems to me to be of thehighest importance, as a piece of ad-ditional information afforded by theMuseum specimen, is the discovery ofwhat I believe to be ihe jointed palpus ofone of the maxillas (Fig. 1), which hasleft an impression upon the side of the hypostoma—just, in fact, inthat position which it must have occupied in life, judging by otherCrustaceans which are furnished with an hypostoma, as Apus,Serolis, e
. Geological magazine. somites, exposed to view,united along the median line by a longi-tudinal ridge. The pseudo - appendages, however,have no evidence of any what seems to me to be of thehighest importance, as a piece of ad-ditional information afforded by theMuseum specimen, is the discovery ofwhat I believe to be ihe jointed palpus ofone of the maxillas (Fig. 1), which hasleft an impression upon the side of the hypostoma—just, in fact, inthat position which it must have occupied in life, judging by otherCrustaceans which are furnished with an hypostoma, as Apus,Serolis, etc. The palpus is 9 lines in length; the basal joint measures 3 lines,and is 2 lines broad, and somewhat triangular in form. There appear to be about seven articulations in the palpus itself,above the basal joint, marked by swellings upon its tubular stemwhich, is one line in diameter. There can be no reason to doubt that the Trilobita possessed an-tennules, antennas, mandibles, maxillge, and maxillipeds, as we find. h. hypostorae ; p. palpus;m. maxilla. Br. H. Woodward— On the Structure of Trilohifes. 79 the same organs preserved in Crustacea of equal antiquity [ acuminata and Eiirypteriis remipes, both Upper Silurianforms). We know of no Crustacean having tivo pairs of appendages to eachsegment; but it is characteristic of Crustacea to have their append-ages hifid, giving rise to an endopodite and an exopodite, but theseare always given off from a common base (basipodite). Having regard to the characters presented by the Trilobita as agroup, we should be inclined to place them neai- to (if not actuallyin) the Isopoda-Normalia. In all this group, the branchia3 are ab-dominal, being placed under the broad and well-developed pygidium,which is not equivalent to the telson of the higher Crustacea, but iscomposed of several segments soldered together, in fact, representingthe true abdomen. It is here, then, we should expect to find thebranchiee in the Trilobites pla
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