REPORT ON THE CRUSTACEA MACRUEA. 89 



found in the lithographic stones of Solenhofen and the lias of Southern England, it has 

 the flagella of the first pair of antennee long, and all the pereipoda suhequal, the first 

 pair not longer or more chelate than the others. 



PcUinurina pygmsBa, Miinst., Palinurina longipes, Miinst., and Cancriwus claviger, 

 Miinst., evidently belong to this family, and probably also Arclneocarapus bowerbankii, 

 M'Coy, from the London clay; the last is remarkable for the length of the first pair of sub- 

 chelate pereiopoda and the prominent rostriform character of the frontal margin of the 

 carapace. 



Development of the Palinuril\e. 



The species belonging to the genera of this tribe are amoug the largest of the Crustacea 

 Madura, measuring as they frequently do some two feet or more in length. But 

 although their dimensions are so great, yet their ova are among the smallest, measuring 

 less than 1 mm. in diameter. As in most instances when the ova are small, their 

 number is correspondingly large. 



The young when it quits the egg measures 1 "5 mm. from between the ophthalmopoda 

 to the posterior extremity of the pleon. The legs, of which one single and four double 

 branched pairs are already well-developed and longer than the animal, and previous to 

 being hatched lie longitudinally rolled up, passing anteriorly between the ophthalmopoda 

 and reaching over the dorsal surface of the animal to the posterior extremity of the 

 cephalon. When it quits the ovum and throws off the first embryonic covering it 

 appears in the form of what was long believed to be a perfect animal, the Phyllosoma. 

 At this period, in specimens that I have taken from the ova of British species (PI. XIIa. 

 fig. 1), the central ocellus is very conspicuous, and placed between the ophthalmopoda 

 which are largely developed and distinctly pedunculated, the ophthalmus being large and 

 massive, and the peduncle rapidly narrowing to a slender attachment. The two pairs of 

 antennas are only uni-branched, and as yet do not appear to be articulated. The 

 mandibles are present and perhaps one of the siagnopoda. 



The pereion is not covered by the carapace but consists of six somites dorsally fused 

 together, and carries five pairs of pereiopoda, of which the first is small, slender and 

 uni-branched ; the others are biramose, the second branch, articulating with the distal 

 extremity of the basis, is multiarticulate, consisting of six subequal joints including the 

 two basal, which are homologous with the coxa and basis. 



The pleon is short, showing at the sides the divisions which mark the number 

 of its somites. 



Unfortunately the young are very difficult to rear, and although they have been 

 occasionally hatched in artificial aquaria, 1 none have yet been known to pass into the 

 second stage of development. 



1 The late Mr. Alfred Lloyd informed me that in the aquarium at the Crystal Palace the young of the Palinurus 

 when first hatched hung in the water as a cloud in the form of an inverted pyramid for some time— two days, if I 

 remember correctly — and then gradually dispersed. 



(ZOOL. CIIALL. EXP. — PART LIT. 1886 ) Fff 12 



