CETJSTACEA OP THE MEEQTJI AECHIPELAaO. 297 



raptorial limbs being armed witb three spines besides tlie elon- 

 gated curved terminal spine, and by the armature of the distal 

 prolongation of the base of the uropoda. But Pseudosquilla 

 pilaensis is so much the more interesting, because it forms a 

 transition from the genus Pseudosquilla to the genus Li/siosquilla, 

 (1) by the eye-peduncles being dilated at the distal end, having 

 the cornea bilobate, (2) by the terminal segment of the post- 

 abdomen being transverse, much broader than long. 



In its outer appearance this species agrees more or less with 

 the Japanese Lysiosquillalatifrons (Fauna Japonica, pi. li. fig. 3). 

 The carapace is but little longer than broad, is little narrowed 

 anteriorly, its antero-lateral angles are rather obtuse, and its 

 postero-lateral ones are broadly rounded. The upper surface 

 is smooth, even when seen under a magnifying- glass, and 

 presents the two ordinary, longitudinal, submedian sutures, which 

 are straight and continuous, from the anterior to the posterior 

 margin, but no transverse cervical suture. As in Pseudo- 

 squilla Cerisii, the rostral plate terminates in a prominent, acute 

 spine, which projects a little beyond the eyes, though not reaching 

 the distal end of the antepenultimate joint of the internal antennsB ; 

 the basal portion of the plate is more than twice as broad as long, 

 and its antero-lateral angles are rather obtuse. The upper 

 surface of the rostral plate is perfectly smooth. The eye- 

 peduncles are short, reaching only to the middle of the ante- 

 penultimate joint of the internal antennae ; they are dilated at 

 their distal ends, and the cornea is bilobate, presenting a larger 

 internal and a somewhat smaller external lobe. The internal 

 antennse have th.e ordinary length, their peduncles being as long 

 as the carapace ; the last joint of the peduncle is a little shorter 

 than the penultimate, whereas in most species of the genus 

 PseudosguiUa it is longer. The flagella of the internal antennae 

 are a little shorter then their peduncles, and the latter does not 

 extend as far forward as the external antennse, which are a little 

 longer. 



The upper surfaces of the four exposed thoracic segments and 

 of the segments of the postabdomen are rounded and smooth ; 

 the first exposed thoracic segment is laterally prolonged into a 

 very short acute lobe, constituting the lateral angles of the 

 posterior margin. The two following are laterally rounded, with 

 entire margins, whereas the last presents a very small subacute 

 prominence. The fifth or antepenultimate segment of the post- 



