1922.] 



S. Kemp : Notes on Crustacea Decapoda. 



189 



TEXT-PIG. 42. — Periclimenes 

 brevicarpalis (Schenkel). 



Telson. 



The sixth segment of the abdomen is about 1*5 times the 

 length of the fifth. The telson (text- 

 fig. 42) is . rounded above with two 

 pairs of very small and inconspicuous 

 dorsal spines. These spines are placed 

 further back than usual, the foremost 

 pair being situated much behind the 

 middle of the telson The terminal 

 spines are unusually thort. The outer 

 uropod is scarcely more than twice as 

 long as broad. At the distal end of 

 its outer margin there is, as usual, a 

 movable spine separating the ciliated 

 and non-ciliated portions of the mar- 

 gin ; but the fixed spine commonly 

 found immediately in front of this 

 movable spine is absent. 



The largest specimen I have seen is 

 a female 31 mm. in length. 



The literature contains a number of 

 references to the marvellous colouration 



of this species when alive and to its association with anemones 

 of the genus Discosoma. Saville-Kent (loc. cit., 1893) has given a 

 coloured drawing of a prawn found on Discosoma haddoni which 

 is perhaps intended for this species, but the figure is extreme- 

 \y poor. Coutiere (loc. cit., 1898), who refers to the prawn as 

 Bithynis sp., says of specimens subsequently described by Nobili 

 as Palaemonella aberrans, — <f Un Palemonide du genre Bithynis 

 Dana merite une mention speciale par son habitat et sa coloration. 

 II est absolument transparent, mais se signale par quelqueS ann- 

 eaux d'un violet pale sur les appendices et l'abdomen, et surtout 

 par des taches d'un blanc nacre eclatant, occupant la region stom- 

 acale tout entiere, le coude de l'abdomen, l'extremite des rames cau- 

 dales et les epimeres du deuxieme segment. Ce magnifique Crustace 

 se tient obstiuement dans la zone de protection que circonscrit une 

 grande Actinie assez commune dans les flaques profondes qui separ- 

 ent les madrepores. Fytale sur le sable, le disque oral de 1' Actinie, 

 de couleur blanchatre, arme d'un tres grand nombre de courts 

 tentacules urticants, atteint souvent o m. 30 de diametre. Bithy- 

 nis se tient dans ce circle, nageant a peu de distance au-dessus, 

 souvent par couples, et se laisse assez aisement capturer a. l'aide 

 d'une eprouvette pleine d'eau que Ton descend doucement sur 

 l'animal.'' 



Lenz (loc. cit., 1905) describes the colour thus, — " Voeltzkow 

 gibt die Farbe im Leben als wasserhell an. Beine an den Gelenk 

 stellen dunkelblau, Korper dunkel und hell., mit rotbraunen und 

 dunkelgelben Flecken ; Scheren an den Seiten mit weissem Langs - 

 streifen. Augenstiele weiss." This description does not agree well 

 with my own observations. 



Miss Rathbun (loc. cit., 1914) has described the colour of a 



