Hirudinea of the Canadian Arctic Expedition, 1913-18. 



By J. Percy Moore 



University of Pe7i7if<y]vania. 



The Canadian Arctic Expedition, from 1913 to I'JIO, yielded a very few 

 leeches. These are contained in four bottles sent to nie along with a few bottles 

 of planarians by Mr. Frits Johansen. There are but two species, already well 

 known from the seas of northern Europe but as they have not lieen recorded 

 previousl}' from American waters it seems worth while to i)ul)lish a notice of 

 the exten;sion of their known geographical range. Both belong to the family 

 Ichthyobdellidse. 



Family ICHTHYOBDELLID^. 



Abranchus scorpii Malm. 



This species, with which A. hrunneus Johansson is probably identical, is 

 represented by nineteen specimens varying from 14 mm. to 40 mm. long and 

 from -8 mm. to 2-7 mm. in maximum diameter. All of the specimens are nearly 

 terete or only very slightly fiattenpd, the young ones most so. The greatest 

 diameter is shorth" behind the middle from which it tapers both ways but 

 unequally. The anterior end is more slender and more gradually tapered but 

 there is no distinct division into two regions. In the better preserved specimens 

 both oral and caudal suckers are large, thin and widely expanded, the oral 

 relatively less so on the larger examples. 



On none of the specimens is the annulation strongh' marked, the somites 

 being dominantly triannulate with the secondary annuli more or less well 

 differentiated. Thus in the widest part of the posterior region the neural or 

 middle primary annulus is enlarged and clearly subdivided into secondary 

 annuli Avhich, however, are smaller than the entire first and third primary 

 annuU so that we have the formula { + h-) <W + > {b'^ + 6). In the an- 

 terior region development of annuli has gone less far, being recognizal)le only 

 in the neural annuh. The formula is, therefore, A^ <{ -\- b^)>A^. The 

 sensillse and larger non-segmental cutaneous sense organs are developed on 

 annulus b^ and a few smaller ones on b^, b- and b'\ 



The fresh colour as described in the collector's notes is "a dark purple- 

 brown main-color; strongest red in shape of segmental bands. The two ter- 

 minal suctorial discs pale inside with the brown muscles shining through. Eyes 

 black." The preserved specimens differ consideral)ly chiefly as a result of 

 size and fading. Those from station 42-" are most deeply pigmented, being 

 of a dark reddish brown above, paler below. The margins of both discs, two 

 transverse bands on the oral disc and radiating lines and marginal spots on 

 the caudal disc, several transverse bands on the body, and the region about 

 the anus also paler. Those from station 49e are pale reddish brown above 

 with whitish transverse bands especially conspicuous laterally on the first 

 annulus (A^) of each somite. All of the parts indicated as pale reddish on the 

 specimens from 42' are on these whitish. Small individuals are nearly 

 colourless. The sensillae and non-segmental sense-organs are clear white and 

 very conspicuous on dark specimens. The three pairs of eyes are black and 

 arranged as figured by Johansson. The caudal eye-spots also are black, small 

 and arranged in a circle at the central ends of the pale marginal spots. 



Following is a list of the specimens with laiiels and collector's notes quoted 

 in full: 



