The type of this small form is only 2.5 mm. long. The pharynx is strongly sinuous. The palpi are contiguous throughout and are fused for most of length though a median furrow or sulcus above and one below run to base; projecting forward; together they narrow distad, with outline triangular; shorter than prostomium. Eyes two pairs, well separated, subequal, forming a nearly straight transverse row a little in front of the peristomium. Median tentacle attached far back between posterior eyes; short, a little exceeding prostomium and palpi together. Lateral tentacles also short, each attached at cephaloectal corner with the prostomium bulging forward between them. Tentacular cirri and notocirri also short, the latter in anterior region about equalling half the width of the body proper and not extending much beyond the tips of the setae; joints short, near fifteen or less in number. Neurocirri subcylindric, slender, reaching ends of parapodia. Setae transparent; end of shaft but little enlarged, its articular edge very oblique; appendage long and slender, the tip curved, the edge strongly fringed. Body ventrally flat, convex dorsally, strongly narrowed caudad. Taken in a sabellid colony. Type--M. C. Z. 2, 151. NEREIDÆ _Nereis latescens_ sp. nov. Allied to _N. vexillosa_ (Grube) but a much smaller species readily distinguishable superficially through the presence of purplish markings on the prostomium and anterior segments, by the form of the appendages, and particularly by the presence on region V of the proboscis of a single large conical tooth such as is present in various epitokes. The prostomium is marked above by a large purplish area germinate by a narrow median longitudinal yellow line. Eyes black. On the anterior segments, above on each side a transverse purplish stripe along anterior and one along posterior border and across the dorsal region, a shorter but broader stripe a little in front of the middle of segment. The body otherwise yellowish. Eyes exceptionally large, and those of each side very close together. Tentacles close together, slenderly cylindrical, moderately narrowing distad, shorter than prostomium and not extending beyond end of proximal joint of palpi. Paragnatha in general as in _vexillosa_; area I with but a single tooth; II, III and IV with numerous teeth in a patch on each; V with a single exceptionally large tooth; VI with four teeth in a quadrangle; VII and VIII with teeth in a band across ventral and lateral surface in which the proximal ventral teeth are smaller than the distal as in _vexillosa_. Peristomium shorter than prostomium and than the next two somites combined; divided by a transverse furrow. Tentacular cirri short; the ventral ones subequal, less than half the length of the dorsals, which are also nearly equal to each other; more or less flattened; cirrophores short. A typical parapodium presents three stout conical lobes additional to the setigerous ones; of these the dorsal