STATE GEOLOGIST. 119 



unevenly but distinctly reticulate shell, slender abdonien, and a 

 strong claw which was dentate. There were several young (more 

 than two), and the shell in these was more regularly reticulate. All 

 efforts to find a second specimen failed, and the one seen was some- 

 what mutilated; hence I am unable to determine its real position. 



XI. — Genus Monospilus, Sars. 



Head separated by a depression from the body; shell high, com- 

 pressed, posterior margin somewhat less than the greatest hight of 

 the shell. Post-abdomen broai, ornamented with lateral and post- 

 erior spines; claws large, with a single basal tooth. The compound 

 eye is absent, its place being taken by the pigment fleck, which is 

 the functional eye. ^ 



Monospiliis elispar, Sars. 



(Plate I. Fi^. 21.) 



Lynceus tenuirostris, fischer, Abli. uebei' einige neue Dapli. uad Lynceidoe. p . 427, 



tab. Ill, figs. 9—10 (fide Sars). 

 Monospilus dispar, saks, Crust. Cladoc. iOmga. af Cliristiania, p. 165. 

 Monospilus dispar, mueller, Danmark's Clad . , p. 196. 



Shell roundish; ventral margin setose; posterior angle rounded, 

 marked above with numerous impressions. Antennules small; an- 

 tennae long, with seven setae- Post-abdomen short and broad, bear- 

 ing a series of spines along the excavated posterior margin, and 

 ornamented on the sides with clusters of bristles. The shell in old 

 individuals is not moulted but remains as in Ilyocryptus, covering 

 the greater part of the new shell. The figure shows an old indivi- 

 dual with its successive coverings still clinging to it. Like Ilyo- 



1 So much interest attaches to this species that -sve reproduce the Latin description of 

 Sars. " Testa in adultibus valvulis composita pluribus, altera alteri imposita, a latere visa 

 lata, latitudine maxima in parte antica sita; margine superiore antice valde prominente, 

 posteriore et inferiore ciliato rotundatis. Caput mobile, perparvum et valde depressum, 

 supine impressione parva sed distincta, a testa cetera disjanctum, deorsum in rostrum rec- 

 tum et breve apice obtuso exiens. Animal supra visum sat compressum, latitudine maxima 

 capite majore ante medium sita. Pars superior testae et capitis impressionibus numerosis 

 rotundatis notata. Antennae 1-mi paris minutse structura ut in ceteris Lynceidis ; 2-di paris 

 sat longse, ramo altero setas 4 et aculeum unum apicalem, altero setas 3 et aculeos duos, 

 quorum alter longus articulo primo ejusdem rami adfixus est, gerunte. Postabdomen breve 

 et latum, apicem versus truncatum ; margine posteriore supra obtuse angulato, ad anguliun 

 inferiorem rotundatum seriebus duabus acu'eorum inque lateribiis setis vel spinulis brevi- 

 bus numerosis prseditum; ungues terminales ad basin aculeo longo armati. Intestinum, ut 

 in ceteris Lynceidis, in thorace laquem fere duplicem format. Macula nigra unica minima 

 prope basin antennarum 2-di paris ; maculae infra oculari in ceteris Lynceidis simillima, in 

 capite conspicitur, quae, quum oculus verus compositus in omnibus ceteris Crustaceis 

 Cladodoceris distinctus omnino ab-it, organum quamquam rudimentare visus habenda est. 

 Animal parum pelluciduni, colore fulvescente. Longit. parum supra ^ mm " 



