OXFORD UNIVERSITY SPITSBERGEN EXPEDITIOISr. 1129 



xiv. and xv. Tliey are small, and the wings do not meet above 

 the cord, all the dorsal surface of the cord being free. The 

 lateral extent of the wings is not great ; each measures about 

 twice the transverse diameter of the cord, and does not reach 

 outwards more than halfv/ay towards the ventral setal bundles. 

 They ai-e not composed of several layers (as in L. nervosus, 

 according to Ude). 



Besides the parasites in the oesophagus, others were found in 

 the testicular region. Here there are a number of sacs, each 

 containing what appear to be stages in the formation of spores. 



It is extremely difficult to know which of the worms described 

 by the older writers, and designated by names tha.t are still in 

 use, correspond to forms met with at the present day. The 

 older descriptions are so very scanty, according to present-day 

 requirements, that they frequently fit several of the species 

 now recognized. In course of time, other descriptions have been 

 published under the older name, supposedly referring to the same 

 worm ; particulars have been taken from these descriptions and 

 incorporated in the diagnoses. The result is a composite picture, 

 which may or may not represent the worm which the original 

 describer had under his eyes. Another woi-m may come up, 

 which may fit the original description equally well — and may 

 therefore be identical with the original species ; but it will have 

 to be described as new, since it is not characterized by the accre- 

 tions which have gathered round the original diagnosis. 



Thus the original description of Liombricillus pagenstecheri 

 (Ratzel) is very scanty, but it has been added to by Yejdovsky 

 and Ude. The present worm seems to differ from the original 

 description (12) in having the setaa fewer in number (2-5 as 

 against 6-10, 7-8 being the commonest numbers in the original), 

 and straight (those of the original, while described as straight, 

 had, nevertheless, a slight curve at their sharp end — " mit leichter 

 Biegung an der scharfen Spitze"), with blunt instead of sharp 

 points. From the diagnosis in the ' Tierreich' (11), which embodies 

 what I have called later accretions, it differs in having small 

 instead of large copulatory glands, which leave the whole of the 

 dorsal surface of the cord uncovered ; and in having the whole of 

 the spermathecal duct closely covered with gland-cells, instead 

 of loosely ; the shape of the cerebral ganglion also differs con- 

 siderably. 



From L. henkingi, described by Ude from Bear Island, the 

 present form differs in not having S- shaped setee, in the origin of 

 the dorsal vessel in xiv. (instead of in xiii.), in having copulatory 

 glands in xiv. and xv. (instead of in xiii, and xiv.), and in the fact 

 that these glands are here very much smaller (in L. henkingi the 

 wings of the glands are four times as extensive as the greatest 

 diameter of the cord, and they reacli outwards somewhat beyond 

 the setal bundles). 



The present species is not very unlike L. franciscmms Eisen, 

 from California (varieties of the species also from Pribilov Islands 



