I. '08. 



19 



these on the completion of their metamorphosis descend to 

 deeper water. Lo Bianco kept some young specimens alive 

 in an aquarium, and found that they always swam head down- 

 wards, as though endeavouring to reach greater depths. 



? Amalopenaeus valens, Smith. 



? Amalopenaeus valens, Smith, 1884, PI. x, tig. 2. 

 ? Gennadas valens, Bouvier, 1908, PL i, fig. 3, PL ix, 

 figs. 1-20. 

 The principal characters of the solitary Irish specimen (a 

 female, 48 mm. in length) are as follows : — 



1. Eyes proportionally slightly larger than in A. clegans. 



2. Second joint of antennular peduncle, measured dorsally, 



fully three-quarters the length of the ultimate joint. 



3. Apical spine of antennal scale extending beyond the lamellar 



portion. 



4. Ultimate joint of mandibular palp four-fifths as long as the 



width of the first joint. 



5. Anterior prominence of merus of second maxillipede slightly 

 less than one-third the total length of the joint. 



Chela of second pereiopod slightly shorter than carpus. 



Merus of third pereiopod very evidently shorter than carpus. 



Thelycum as in text figure ; its principal features being a 

 single large plate, almost round, between the fifth pair 

 of pereiopods, and a pair of triangular plates furnished 

 with a few stiff setae at the base of the fourth pair. 



Amalopenaeus valens (.?), Thelycum. 



The branchial formula is the same as in A. elegans. The 

 colouring is also much the same as in that species ; the deep 

 blue pigment has almost exactly the same distribution,^ but 

 the black spot on the dorsal aspect of the eyestalk behind the 

 cornea is almost obsolete. 



1 Neither this specimen nor numerous examples of A. elegans 

 (examined when freshly caught) showed such large areas of dark blue 

 pigment on the abdomen as are depicted by Bouvier for valens (1908, 

 PL I, fig. 3); otherwise this coloured illustration gives an excellent idea 

 of the appearance of Irish sp»cimens of this genus. 



B 2 



