170 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.5 



Genus PSEUDOSQUILLA Dana, 1852 



Many species of Pseudosquilla and Lysiosquilla seem to have much 

 in common. As similar-appearing species ascribed to one or the other of 

 these genera are examined, it becomes evident that the presence of a 

 rather distinct median longitudinal crest or carina on the telson, coupled 

 w^ith the absence of denticles or, rather, spinules^^ between a pair of 

 movable submedian spines or "teeth" on the hind margin of the telson in 

 the adult, is the chief character distinguishing representatives of the 

 former from those of the latter which most resemble them {i.e., Lysio- 

 squillas of the second type of Kemp). 



The Pseudosquillas seem to fall quite naturally into 2 groups on the 

 basis of the number of joints comprising the shorter ramus of the 6th, 

 7th, and 8th pairs of thoracic legs. This shorter ramus is composed of 2 

 joints in P. lessonii, cerisii, ferussaci, pilaensis, veleronis, and I believe 

 also in P. dofleini, of which I have seen no specimen, but which its author 

 considered morphologically intermediate between the first 2 species. It 

 will be observed that this grouping also corresponds with the B section 

 (p. 96) of the key in Kemp's Monograph. 



In the other group, the shorter ramus is composed of but a single 

 joint or segment and here belong P. ciliata, ornata, oculata, megaloph- 

 thalma, and perhaps also oxyrhyncha, which also I have not seen. How- 

 ever, the last-named species, on the basis of Komai's remarks,'*^ is no 

 doubt a synonym of P. ornata and so may not need to be further con- 

 sidered. These species all belong to the A section of Kemp's key. There is 

 a very interesting character that the species in this group or section possess 

 in common. That is the structure which Kemp mentions as occurring 

 in Pseudosquilla ciliata and its immediate allies, a curious process spring- 

 ing from the dorsal aspect of the antennal protopodite. "This consists 

 of a flat, elongated plate [more or less channeled in some species], 

 directed forwards, and provided inferiorly with a deep vertical keel." 



43 Submedian spinules persist in some species of Pseudosquilla, at least until 

 the so-called first littoral stage. In certain species of Lysiosquilla, species of the first 

 type (Kemp, Mem. Indian Mus., Vol. 13, No. 4, p. 109, 1913) such as L. maculata, 

 without dorsal spines on the telson, but which have the posterior margin of the 

 telson unarmed or cut into a few large, blunt teeth, there are neither submedian 

 spines nor teeth, nor submedian spinules distinguishable as such on the hinder 

 margin. 



44 Mem. Coll. Sci. Kyoto Imper. Univ., Ser. B, Vol. 3, No. 3, Art. 4, p. 324, pi. 

 14, figs. 2-2b, 1927; Annot. Zool. Jap., Vol. 7, Nos. 3, 4, p. 268, 1938. 



