34 G. O. Sars. 



tion carrying the caudal setæ being greatly produced. Ephip- 

 pium triangular, coarsely sculptured in the middle, and con- 

 taining 2 resting eggs. Male very much smaller than fe- 

 male, and easily recognizable by the great development of 

 the antennulæ, which are almost twice as large and some- 

 what procurved, with a strong bristle at the base anteriorly, 

 and beyond it 4 closely-set transverse rows of rigid hairs, 

 the outer part being quite smooth. Claw of 1st pair of 

 legs very slender and abruptly bent at the base, termina- 

 ting in an obtuse point, which is formed by 3 superposed 

 lamellæ. Caudal part rather unlike that of the female, be- 

 ing produced at the end to a long cylindric tube containing 

 a common ejaculatory duct for the sperm, dorsal edge above 

 the anal orifice smooth, not as in female serrate. Colour of 

 female more or less bright orange. Length of female reach- 

 ing 1 mm., that of male 0.40 mm. 



Remarks. — This form seems to be nearly allied 

 to the European species generally recorded as M. rosea 

 (Jurine) 1 ). It differs, however, in some points, both in the fe- 

 male and male characters, and ought therefore more properly 

 to be regarded as a distinct species. The transformation of 

 the caudal part in the male of the present form (see figs. 6, 9) 

 is very remarkable. According to Prof. Lilljeborg, also the 

 male of the species, named by him M. rosea, has this part 

 produced at the tip, but the apical prolongation is here coni- 

 cally tapered, whereas in the present species it is cylindrical 



x ) I think, however, that this form is not Jurine' s species, differ- 

 ing, as it does, very conspicuously, not only in the colour, but also in 

 the shape of the head. In both these respects another species, which 

 I have succeeded in raising from dried mud from Algiers, agrees per- 

 fectly with the figure given in Jurine's work, and this form, to be 

 described on another occasion, I accordingly regard as the true Mon- 

 oculus roseus of Jurine. 



