274 Messrs. J. Wood-Mason and A. Alcock on 



Both the preceding arc remarkable for tlie membranous 

 condition of the lower part of the branchiostegite in apparent 

 correlation with the voluminous and feathery character of the 

 branchiae. 



7. Metapenceus rectacutus (Sp. Bate). 



Penceus rectacutus, Sp. Bate, ' Challenger ' Macrura, 1838, p. 2GG, 

 pi. xxvi. fi<r. 2 (excl. 2 s), $ . 



I'wo fine females from Station llo, 188 to 229 fathoms. 



Colour in life red. 



The carapace and abdomen are perfectly glabrous through- 

 out. The former is armed with three spines, an antennal, an 

 hepatic, and a branchiostegal. From the last-named of these 

 a sharp crest curves boldly upwards and backwards, forming 

 the lower boundary of the anterior end of the cervical groove 

 as far as the level of the hepatic spine, whence it is continued 

 nearly to the ])Osterior end of the carapace as a blunt ridge — 

 the cardio-branchial — which, with the branchiostegal crest, 

 marks out the upper boundary of the subjacent branchial 

 chamber ; similarly, a sharp crest continued straight upwards 

 and backwards from the hepatic spine accentuates the gastro- 

 he])atic groove. 



The 13- to 14-toothed rostrum is neither quite so stout nor 

 quite so straight as represented by Spence Bate. The exo- 

 podites of the thoracic legs are rudimentary. The all but 

 equal antennulary Hagella are about as much shorter than 

 the cara])ace, measured from tiie frontal to the middle of the 

 posterior margin in a straight line, as they are longer than 

 the rostrum measured from the same point in the same 

 manner. 



The telson is strongly trifurcate and armed at the sides, in 

 front of the lateral prongs, with three pairs of small movably- 

 articulated spines, which are separated from one another and 

 from the lateral prongs by intervals equal to about twice their 

 own length. 



The branciiial formula is : — 



l + -"J<y'. + -"i + <i + o =ir + ;5,y.. 



