ECHINODERMATA. 521 



description of some new marine Planarias. One of these, 

 which he has named P. [?] oceanica, is characterized by two 

 ear-like processes, situate upon the neck-shaped anterior 

 extremity of the body. Planar ia formosa, another marine 

 Plauaria, has no exsertile mouth-sucker, but four groups of. 

 ocelli on the anterior part of the back, and is characterized 

 by red, purple, and white markings. A third species has 

 been named by Darwin Planaria [?] macrostoma, the 

 anterior extremity of the body is square, truncate, and can 

 be employed as a suctorial acetabulum. On its neck are 

 two large black ocellar spots, whilst the alimentary orifice, 

 with an extremely long mouth-sucker, is situated in the pos- 

 terior half of the body. A fourth species, Planaria [?] 

 incisa, presents a sinuous-toothed, anteriorly deeply 

 indented, margin, which at the anterior edge supports very 

 numerous crowded ocelli. In the median line of the abdo- 

 minal surface four apertures are placed, one behind the 

 other, of which the penultimate is an oral orifice, from which 

 a thin, much folded, sinuated mouth- sucker can be pro- 

 truded, and which, when extended, is quite as wide as the 

 body. On a fifth species Darwin has founded the new genus 

 Diplanaria, which is characterized by a double alimentary 

 orifice, with two exsertile mouth-suckers, and behind which 

 two genital orifices are placed. Its ocelli are collected into 

 four groups. The only species, Diplanaria notabilis, occurs 

 under stones [in tidal pools], but also swims freely in the 

 sea water by the movements of its toothed foot-border. 



ECHINODERMATA. 



Sipunculus capitatus has been described as new by 

 Rathke (Nov. Act. Natur. Curios, t. xx, P. i, 1843, p. 143.) 

 The animal has a thick cephalic extremity, with a long con- 

 stricted neck, and the oral orifice is furnished with about 

 fifteen flattened, lanceolate tentacles. The middle portion of 

 the body is surrounded with a belt of minute blackish 



