530 PROCEEDINGS OF THE ACADEMY OF [Jwly, 



of sponge or organic debris. On each side is a broad ridge where the 

 dorsal setse rise above the felt, each one or tuft supporting a thick vest- 

 ment of the deposit, which increases its thickness many fold and ad- 

 heres with great tenacity. When this deposit, together with the super- 

 ficial layer of felt supporting it, is cleared from the back a deeper clean 

 layer of felt is exposed, through which the elytra are visible. 



There are 14 pairs of the latter situated on somites II, IV, V, VII, 

 IX, XI, XIII, XV, XVII, XIX, XXI, XXIII, XXVI and XXIX. 

 Owing to their very small size and the softness of the tissues the posi- 

 tion of the last 2 or 3 pairs is somewhat doubtful, but as they seem to 

 occupy the positions usual in other species these determinations are 

 probabl}^ correct. This count was made on but one specimen and a 

 fifteenth pair may be expected to occur on better preserved material. 

 The elytra are smooth, thin, transparent and colorless, without mark- 

 ings or papillse of any kind. The anterior and middle ones are orljicular, 

 with large, narrow scars nmning from the lateral margin to the center; 

 the posterior five are very thin, folded longitudinally, elongated, over- 

 lapping, with anterior attachment and free posterior ends. 



The parapodia are well developed and prominent throughout, rela- 

 tively more so than in most species of sea-mice. Typical parapodia 

 (fig. 4) have a prominent, rather slender, elongated, slightly compressed 

 neuropodium, its end fashioned into three inverted steps sloping up- 

 ward and outward. Like the ventral surface of the body the neuro- 

 podium is studded, especially below, with spherical papilla?. The ven- 

 tral cirrus arises from a short base somewhat on the'posterior surface 

 proximad of the middle of the ventral border. Its style is slender, 

 tapering, balled at the tip, and reaches nearly to the end of the neuro- 

 podium. The notopodium is more elevated than usual in the genus 

 and forms a broad tubercle which slopes on to the back and bears pos- 

 teriorly a prominent ceratophore from which the long slender style of 

 the dorsal cirrus arises. The latter is 2\ to 2^ times the length of the 

 neuropodium, is slender and regularly tapered for f of its length, then 

 slightly enlarged and again tapered to a terminal ball with thickened 

 cuticle perforated at the end for sensory hairs. These cirri rise 

 above the felt and their ends often appear above the material 

 deposited on the back. Toward the ends of the body the parapodia 

 become both much smaller and more slender; posteriorly they are 

 directed caudally and their dorsal cirri are much elongated ; anteriorly 

 the first is bent forward by the sides of the prostomium and bears a 

 tuft of slender setse and the tentacular cirri at its end. The ventral 

 cirrus of the second parapodium approaches the dorsal in size and form. 



