53 



posterior pedigerous segments coalesced. Cephalosome obtusely produced in front, 

 being fully as long as it is broad at the base. Pleopoda, as in male, natatory. 

 Body whitish, mottled all over with reddish brown specks. Length of male 5 mm., 

 of female about the same. 



Hernarlis. — The identification of this form with Montagu's species is some- 

 what doubtful; but as, at least off the coasts of Norway, it is by far the most 

 common species, I am much inclined to believe, that it is the form originally de- 

 scribed as Cancer maxillaris. The form recorded by Sp. Bate & Westwood under 

 this name is a very different species, showing in some resjDects a closer relation- 

 ship to the following species, though apparently specifically distinct. The pre- 

 sent species may be easily distinguished in both sexes from the 3 other Norwegian 

 species, the male especially being readily recognized by the very large lanceolate 

 mandibles, and by the very pronounced areolation of the dorsal face of the head, 

 the female, by the form of the cephalosome. 



Occurrence. — I have met with this form rather abundantly along the whole 

 south and west coasts of Norway, from the Christiania Fjord up to the Lofoten 

 Islands, in depths varying from 20 to 100 fathoms, and generally on muddy bottom, 

 Male specimens are much more frequent than female ones, both being always 

 found slowly creejjing on the bottom. The larvse (Praniza) are much more agile, 

 and are often seen swimming about with great speed. Occasionally I have found 

 them clinging to the skin of living fishes of various kinds, when just brought up 

 by the fishing-line. In such cases, the posterior part of the mesosome generally forms 

 a greatly swollen, unsegmented division (see PI. XXII, fig. 1) filled with the blood of 

 their hosts, and this is, on the whole, invariably the case with more advanced 

 larvse, even when taken up by the dredge. In all probability, they all lead a true 

 parasitic existence, but being well fitted for swimming, they may at times leave 

 their hosts. I have once witnessed the transformation of a Praniza (larva) into 

 the adult male form (Anceus). Immediately after the transformation, the integu- 

 ments of the animal were still rather soft, semipellucid, and mottled all over with 

 reddish brown specks, as in the larva, without as yet showing the distinct areolation 

 of the dorsal face of the head, which distinguishes the fully grown male. 



Distribution. — British Isles (Mont.), Kattegat (Meinert), coast of France 

 (Hesse). 



