DONDERSIA CALIFORNICA. 155 



prominent in the majority of species. On the .sides of the organ the epithelium 

 is comparatively thin but it rajiiclly becomes thicker above and below owing 

 to the excessive development of numerous gland cells. In this highly developed 

 condition each cell is a goblet-shaped body with very slender stem and a slightly 

 expanded base in which the nucleus is placed. The secretion consists of a 

 granular mass much like yolk in appearance and staining reaction. Among 

 these larger elements slender supporting cells, usually with subcent rally ])lac('d 

 spindle-shaped nuclei, occur in considerable numbers. Both of these elements 

 occur on the sides of the organ but as mentioned previously they are very lf)w 

 and cubical or rectangular. Since the distal portions of these cells are dislodged 

 in the apparently normal process of liberating the secretion it is probable that 

 at times these lining cells are of greater height. At the postero-ventral surface 

 of the gland a short narrow duct, whose position and general appearance are 

 represented (Plate 8, fig. 3), makes its way into the cloaca. 



Owing to the similarity of the nerves and connective tissue, and muscle 

 fibres, and the consequent difficulty of tracing these to any extent, the nervous 

 system has not been examined. 



Dondersia calif ornica, sp. no v. 



One immature specimen taken at a depth of twenty-one fathoms off south- 

 ern California (Sta. 4303) is the sole representative of this sjxH-ies. Owing to 

 the fact that it bore a superficial resemblance to several small nemerteans it 

 was killed with them in corrosive acetic destroying totally all traces of cal- 

 careous structures. 



The general form of the body is shown (Plate 3, fig. 9). The length is 7 mm. 

 and the greatest diameter 1.2 nmi. The pedal groove, and single, included fold, 

 is continuous with the cloaca though at the point of union the former has be- 

 come very indistinct. The outlet of the anterior pedal gland is a well-marked 

 invagination with highly folded, ciliated walls. In this genus more than one 

 dorso-terminal sense organ is present, two being found in D. festiva and three 

 in D. annulata according to Nierstrasz ('02). In the present species eleven 

 exist, all constructed on the same plan (Plate 35, fig. 12). Of these five occur 

 along the mid line, and the others are not far removed from it. As Plate 6, 

 fig. 2, shows they are not symmetrically disposed for of the six not in the mid 

 line five are on the left side of the body. Each organ consists of a globular mass 

 of slender cells, with elongated mesially placed nuclei, covered distally with a 

 thin continuation of the cuticle investing the body. From the bases of the cells 



