Parker. — On the Structure of the Head in Paliuurus. 307 



I am greatly indebted to Mr. T. F. Cheeseman, F.L.S., of the Auckland 

 Museum, for procuring me a spirit specimen of Palinurus vulgaris, and to 

 Mr. W. A.'Haswell, M.A., and Mr. T. W. Kirk, M.A., for much needed 

 information respecting species of Palinurus in the Sydney and Wellington 

 Museums of which I was unable to obtain either specimens or accurate 

 descriptions. 



I shall be very grateful to anyone who will furnish me with descriptions 

 of the head in Palinurus longimanus, M.-E., P. frontalis, M.-E., Palimtrellus, 

 Boas, and Palinustus, Alph. M.-E., or, still better, who will procure me speci- 

 mens of these forms. 



EXPLANATION OP PLATE XXV. 



Reference Letters, 

 ant. 1, antennule. 



ant. V, articular cavity for antennule. 



ant. 2, antenna. 



ant. 2', articular cavity for antenna. 



ant. st., antennulary sternum. ' 



be, basicerite. 



cl.pr., clasping processes. 



e., eye-stalk. 



e. cx.pl., external coxal plates. 



ep., epistoma. 



epm.pl., epimeral plates. 



fl., flap of movable part of stridulating organ. 



g., groove on lateral surface of antennulary sternum, for tubercle (t.). 



h., dorso-internal hinge of antenna. 



i. cx.pl., internal coxal plates. 



oph. , ophthalmic segment. 



p., ridged pad of movable part of stridulating organ. 



p. ex. pi., posterior coxal plates. 



prc.pr., procephalic processes. 



?'., ridge on antennulary sternum. 



s., smooth surface on antennulary sternum forming fixed part of stridulating organ. 



s. or. sp., supra-orbital spines. 



t., guiding tubercle of movable portion of stridulating organ. 



N.B.— All the figures are diagrammatic, unessential details (spines, tubercles, etc.) 

 being omitted. 



Fig. 1. Longitudinal vertical section of the head of Palinurus edwardsii. 

 "' " » )> ,j Palinurus vulgaris. 



" m » j> i, ,, Palinurus interruptus. 



4. Anterior part of head of Palinurus edwardsii seen from above. 



5- j) ,, Palinurus vulgaris. ,, 



6- >, „ Palinurus interruptus. „ 



7. Antennulary sternum of Palinurus vulgaris, from the left side. 



8. Proximal end of antenna of Palinurus vulgaris, from the inner side. 



