Art. IV. Description of a new Crus/artons Animal found on the 

 Shores of the Soi;th S^hetland hlamh, irifh Remarks on 

 their JVatural History. By James Eights, Naturalist to the 

 Exploring Expedition of 1830. and Corresponding Member of 



CRUSTACEA. 

 MALACOSTRACA. 



Animal broatl-oval, much depressed, trilobate, lobes formed by 

 a slightly impressed sulcus ; divided from the head downwards 



solid and calcareous. Eyes two, superior, sessile and immovea- 

 ble. Antcnn(B four, on a line with the margin of the shell. Mouth 

 inferior, composed of a labrum, two mandibles bearing palpi, two 

 pair of maxillae, tongue, and a labium formed of the first foot-jaws. 

 Feet fourteen, anterior four with a dilated hand, and an incurved 

 moveable finger, remaining ten unguiculate. Branchia: situated 



appendages on its lateral edge, inferiorly it supports four pairs of 

 diaphanous laminae. 



B. TRILOBITOIDES. 

 Head approaching the segment of a circle, descending from the 

 vertex to its anterior portion, and laterally to the edge of the mar- 

 broad sinus, having a narrow, raised and reflected rim, furcate at 

 each extremity : posterior edge gently elevated, sinuous, and cor- 

 responding to the articulation of the abdomen. Eyes elevated 

 and prominent : cornea oblong, lunulate, reticulate, composed of 

 an infinite number of facets, distinctly visible to the naked eye : 

 colour blue, the superior surface covered by an irregular calcare- 

 ous incrustation : from the posterior and external angle of the eye 

 extends a suture forward and outward, dividing the front and an- 

 terior portion of the head from its lateral expansion ; at the origin 

 of the suture commences a transverse furrow, overshadowed by a 



