Nasal Flap Research Articles

Animal Plasticity and Environment

WHILE recently making a zoological collection in the Sevoke River in the Teesta Valley at the base of the Darjiling Himalayas, I observed remarkable differences between the individuals of a Cobitid fish, Acanthophthalmus pangia (H. B.), collected from two diverse ‘niches’ in the same habitat. In Fig. 1 are shown the two types of individuals. The chief difference, which is readily noticeable in the two drawings, is that in the lower drawing the ventral fins are present, while in the upper these structures are totally absent. There are also other differences of a minor nature; for example, the extent of the nasal flap and the form of the caudal fin. Two specimens* possessing ventral fins were obtained from among pebbles and shingle in a swift current, whereas 18 examples devoid of ventral fins were netted from among debris at the bottom of pools in the course of the stream.

Lernaeopoda globosa n. sp., a Parasitic Copepod of Scyllium canicula

Habitat and Record. On 10. iv. 1918 my attention was called to five specimens of Lernaeopoda occurring on Scyllium canicula obtained at Plymouth. The largest copepod was attached outside and about one inch ventral to the left spiracle. The other four were deeply concealed within the left nasal groove, so that the nasal flap had to be cut away in order to detach the parasites. These specimens exhibit characters of their own which seem to combine those of other established species. The most striking modification is that the ends of the attaching “arms” (2nd maxillae) are expanded into large discs on either side of a vestigial bulla, thus recalling L. bidiscalis Kane, 1892, though that species is described as possessing discs of a different conformation, and as having no bulla. In other respects they agree more with L. musteli Thomson, 1899, notably as to their small size, and the proportion of the arms to their trunk. But to these points I do not attach much importance, since both may be due to the confined space in which the parasites are domiciled.