OAR-FOOTED GROUP 



3251 



limbless segments, but the last bears a pair of processes severally tipped with a tuft 

 of four long bristles. The eggs are carried by the mother in a couple of oval 

 sacs attached to the last segment of the thorax, and so prolific are these creatures, 

 that a female, it has been calculated, will in a year produce over four thousand 

 million young. The young when hatched is an oval Nauplius (ft), which gradually 

 acquires the characteristics of the adult. Closely resembling the preceding is the 

 marine Cetochilus, which is devoured in large quantities by whalebone whales. 

 These crustaceans are of a bright red color, and when seen in myriads give the sea 

 the appearance of being stained with blood. 



SPINY-TAILED WATER FI.EA, Acanthocercus. 

 (Much enlarged.) 



The Copepods hitherto noticed are spoken of as the Eucopepoda, but we now- 

 come to a number of genera which have taken to a parasitic life, these Epizoa or 

 Parasitica, being strangely unlike the higher forms. As one of the least modified 

 types, may be mentioned the carp louse (Argulus}. Of the more degenerate 

 types, the structure is exemplified in the cut on p. 3250. In these the body may 

 be broad and flat, as Caligus (e), which is frequently found upon the codfish and 

 the brill, or long and worm-like, as in Lernceonema and Pennella (a and c), the 

 former being a common parasite on the herring and sprat, while in Lern&a, the gill 

 sucker, to which Hcemobaphes (d) is allied, the body is swollen and twisted in the 

 form of the letter S. The two long processes represented in the figures projecting 



