436 PART II. SYSTEMATIC ACCOUNT 



(Fig. \69F). In this regard it is very like the genus Diplobrachia (pp. 369, 

 372). Lamellisabella ivanovi is like L. zachsi in many features: thus, in both 

 species, the ventral ends of the keels of the bridle are not fused together and 

 there is no sharp, upstanding crest on the keels. The keels, however, are 

 almost twice as broad as in L. zachsi. The Panamanian species is similar to 

 L.johanssoni in the comparatively small number of tentacles, in the composi- 

 tion of the tentacular cylinder and in the segmentation of the tube. The 

 characteristics of the species of Lamellisabella are compared in Table 6. 



The tentacular crown is 12 mm long, the fore-part of the body с 3 mm; 

 the mesosoma is 1 mm broad; the horseshoe-shaped plaques are 75/x and 

 the toothed platelets 21/x long. 



The tube is dark, opaque, stout-walled and distinctly divided into segments 

 which are as long as the tube is wide, or just a little larger. 



Material: Kirkegaard had a single incomplete, badly preserved specimen. 



Locality: Gulf of Panama (5°44'N, 79°20'W). 



Depth: 2950-3190 m. 



[4. Lamellisabella minuta sp. nov. Ivanov (Figs. A169-E169) 



In February, 1960, R.V. Vityaz\ working off the southwest coast of India, 

 found, at a depth of 1300 m, a new species of Lamellisabella, which in view 

 of its surprisingly small size I propose to call Lamellisabella minuta. The 

 material consists of two almost complete animals in rather long tubes, and 

 five small fragments of tubes, two of which contained scraps of the trunk. 



The cylindrical fore-part of the body lacks any external boundary between 

 protosoma and mesosoma (Fig. A 169, В 169). In comparison with that of 

 other species of this genus it is greatly elongated, with a length to breadth 

 ratio in one individual of 5 : 1 and in the other 6:1. The small cephalic 

 lobe is somewhat dorso-ventrally flattened and shaped like an equilateral 

 triangle (Fig. B169Z?, C). The cylindrical tentacular crown consists of ten 

 tentacles, each stuck lengthwise to the next (Fig. A169). Inside the crown 

 there is a wide intertentacular cavity, into which project the small pinnules, 

 which are arranged in very thick-set rows along the inner sides of the 

 tentacles. 



The bridle lies in the middle of the fore-part of the body. Each keel 

 consists of a thin colourless cuticular axis with a broad yellow-brown band 

 attached behind it on the ventral side. This band broadens out gradually 

 towards the ventral end of the keel and consists of a row of cuticular bodies 

 which merge into one another (Fig. C169^/). The very thin curved dorsal 



