Arenicola assivtilis 127 



latter difference, which was discussed in its taxonomic bearings, 

 was regarded as unimportant (see p. G9). The difference in number 

 of segments between the Fuegian and New Zealand examples, 

 though striking, was not thought to be sufficient to justify the 

 erection of a new species, in view of the fact that in all other points 

 the two series of examples presented complete agreement. The 

 presence in A. assimilis of two forms, one with twenty, the otlier 

 with nineteen chaetiferous segments, seemed, however, to call for 

 some recognition, seeing that in other caudate species the number 

 of chaetiferous segments is constant. The New Zealand specimens 

 were therefore referred to a new variety, to which the name nffiais 

 was given, indicating its close connection with, and resemblance to, 

 the type. In the same memoir were described, from the Falkland 

 Islands, post-larval and adult specimens, the latter agreeing with 

 those from New Zealand except in the form of the statoliths. From 

 the series of examples studied a full diagnosis of the species 

 was given. 



Observations on the Kecokds. — Prof. Ehlers, in his original 

 account, recorded examples of A. assimilis from Punta Arenas, 

 Uschuaia, Lapataia Nueva, South Georgia and California. The adult 

 specimens from Punta Arenas,^ Uschuaia ^ and South (leorgia^ have 

 twenty chaetiferous segments, and are typical examples of the species. 

 Those from Lapataia Nueva ^ and a young abranchiate specimen, 

 6*5 mm. long, found among the "roots" of seaweeds at Uschuaia,- 

 have nineteen segments, and are thus referable to the variety ajfinis. 

 The inclusion of California in the range of distribution of this 

 species is erroneous, for it rests on a specimen in the Gottingen 

 Museum which Prof. Ehlers referred to A. assimilis solely because 

 he found it to agree with this species in the anangement of 

 its gills (of which there were only twelve pairs). The writer 

 has shown (p. 120) that this specimen belongs to the species 

 A. pvsilla. 



Prof. Ehlers' second memoir gives an acklitioual station for the 

 species, namely, Susanna Cove. 1'he writer has examined the original 



' The writer has examined the original specimens from these stations, 

 preserved in the Naturhistorisches Museum, Hamburg. 



■ This is the only station from which both the typical form and the variety 

 (represented by a single post-larval specimen) have been recorded. Adults of 

 the typical and varietal form occur, however, not far from one another in 

 the Beagle Channel — at Uschuaia and Lapataia Nueva respectively-, and in 

 the Strait of Magellan, at Punta Arenas and Susanna Cove x-espectively. 



