28 AUGUSTA ÄRNBÄCK-CHRISTIE-LINDE, NORTHERN AND ARCTIC INVERTEBRATES. 



Cnemidocarpa mortenseni Hartmeyer 1912. 



Syn. Tethyum (Styela) mortenseni, Hartmeyer 1912, Van Name 1912. 



Distribution: Skagerrack, between Norway and Denmark, 58° 06' N — 9° E. Depth 660—420 in, 

 1 sp. — East coast of North America, 42° 30' 15" N— 70° 38' W. Depth 45 fms, muddy bottom, 1 sp; D:o 

 44° 26' N— 62° 10' W. Depth 127 fms, dark brown mud, 2 sps. 



Cnemidocarpa mollispina n. sj). 



Pl. 2, figs. 23—26. Text-figs. 1 — 2. 



Habitat : 



Kola Peninsula: Litza, 35 fms, sand, 1 sp (August 5, 1877, Sandeberg's Exp.). 

 The unique specimen was collected along with a Molguloid, a form of Eugyrioides. 



Description. 



External Appearance. 



The single specimen of the collection is of almost globular form. The upper 

 side, i. e. the dorsal side, is somewhat flattened. The apertures are piaced on the 

 dorsal side, not far apart. They are four-lobed, small, and cannot be easily distin- 

 guished; the lobes of the atrial aperture are more distinct than those of the bran- 

 chial one. The surface of the test is provided with irregularly formed processes or 

 spines of soft consistence. It is incrusted with large sand grains and shell fragments, 

 between which the pointed processes are discernible. From the ventral side a root- 

 like stalk of great length arises (Pl. 2, fig. 23). 



The specimen measures 6 mm. in length (baso-apical) and 7 mm. in breadth 

 (dorso-ventral). 



Internal Structure. 



The test consists of a thin and very tough tissue which sends forth pointed 

 processes covering the whole surface. It is penetrated by a system of large blood- 

 vessels ending in rather wide bulbs as appears from text-fig. 1 drawn from a hori- 

 zontal section. The mantle adheres to the inner side of the test and the mantle- 

 musculature is well developed. The superficial layer consisting of transverse muscles, 

 and the deeper layer consisting of longitudinal muscles form fairly continuous sheets. 

 The oral tentacles are about 15 in number; they are simple and of three sizes. 

 The atrial tentacles are piaced in one row at the base of the velum. The dorsal 

 lamina is plain-edged. The dorsal tubercle is situated by the side of the ganglion 

 (ef. Pl. 2, fig. 25). Its opening is elongated and curved, not quite semicircular, the 

 open interval is directed to the left. The ganglion is strongly developed; it is 

 piaced to the left of the dorsal tubercle. 



The folds of the branchial sac are all rudimentary. They are represented 



