182 PART II. SYSTEMATIC ACCOUNT 



Fig. 8), while others have none. The diameter of the tube, also, varies from 

 individual to individual within very wide limits (a variation of 0-9-0-91 mm), 

 in a way that is not found in other species of Siboglinum. Though the investi- 

 gations of Caullery are of extraordinary value and interest, being of great 

 importance for the understanding of the Pogonophora, they are, unfortu- 

 nately, of little use as regards the accurate diagnosis of the species of 

 Siboglinum. 



[Since the publication of the Russian edition of this work Dr. Eve South- 

 ward has had the opportunity of examining Caullery's original specimens 

 from the Siboga Expedition and has published a monograph on this material, 

 which she has shown to contain not less than 16 species belonging to 4 or 

 more genera. She writes: 



"In deciding which species should provide the type specimen (lectotype) 

 of Siboglinum weberi I have considered that it should be common in the 

 collection, should provide sufficient material for a complete description, and 

 should possess, as far as possible, all the characters noted as typical by 

 Caullery (1914, 1944). I have chosen a small species which has tubes about 

 0-1 mm in diameter, with regular coloured rings on the walls. These rings 

 are often arranged in pairs. The animal has all the characters of Siboglinum 

 as described by Caullery, including two girdles of platelets around the trunk. 

 This species is the one shown in Caullery's Figs. 9 and 10, and may be the 

 one shown in his Fig. 3 (Caullery, 1944)." (Southward, 1961). 



The following description and the accompanying figure (Fig. 96) are 

 reproduced from Dr. Southward's monograph, by kind permission of the 

 author and the publisher, E. J. Brill. Paragraphs and sentences have been 

 transposed to bring the description into line with the form adopted here. 



"The fore-part of the body is from 0-6 to 1-2 mm long (the average for 

 23 specimens is 0-9 mm), and this length is 7 to 12 times the diameter of this 

 part of the body. The protosoma has a small, slightly pointed cephalic lobe 

 and the tentacle is attached about 0-1 mm behind the tip (Fig. %D, E). This 

 tentacle is often coiled into a spiral but where it is not coiled the diameter is 

 only about 30ju.; it bears one row of pinnules, each about 60/x long (Fig. %F). 

 The row of pinnules begins close to the head of the animal and continues to 

 the tip of the tentacle. There is no pretentacular groove visible but there is a 

 slight transverse groove just behind the base of the tentacle, on the ventral 

 side only. A little farther back there is a fairly well-marked annular groove 

 separating the protosoma and mesosoma, which is followed by an annular or 

 semi-annular groove just before the bridle. In some specimens there is a 

 shallow longitudinal furrow between the third groove and the ventral part of 



