No. 2194. NORTH AMEIilVAN PARASITIC C0PEP0D8— WILSON. 105 



into the latter just in front of the vulvae. Here each egg is covered 

 with a membrane of the cement substance and then passes into the 

 outer case, where it is again flattened and packed w'ith its fellows 

 in a single row. These eggs are much smaller in diameter than those 

 of the other subfamilies, and as a rule there are many more of them 

 than in the Lernaeenicinae and about the same number as in the 

 Lernaeinae. The larva probably hatches as a typical nauplius, 

 although this has never been observed, and is transformed into a 

 metanauplius while swimming freely in the plankton. At the first 

 copepodid stage the larva seeks its temporary host, which in the 

 present instance is a cephalopod, upon whose gills are passed this and 

 the subsequent copepodid stages. At first the larva fastens with its 

 chelate second antennae, but with the first molt it develops a frontal 

 filament by which it is securely anchored to the gill of the cephalopod. 



Then follow pupal stages in which the segmentation of the body 

 and its appendages becomes indistinct, the setae lose their plumes, 

 and the various appendages become misshapen, swollen, and incapable 

 of use. But sexual ripening goes on just the same and fertilization 

 takes place here on the cephalopod's gills. Then comes a final molt 

 for the female in which she acquires again well-formed appendages 

 capable of good service. She then swims away in search of a final 

 host, into whose flesh she burrows and is anchored by chitin horns 

 growing out from the cephalothorax. 



It is worthy of note that some species of this subfamily liaA'^e been 

 found upon whales and become thus the only copepods parasitic upon 

 a warm-blooded animal. It may also be noticed that the members 

 of this subfamily are the largest of the Lernaeidae, sometimes attain- 

 ing the comparatively enormous length of nine or ten inches. 



Genus PENNELLA Oken. 



Pennatula Linnaeus, Systema Naturae, 1758, p. 819. P. sagitta, third 



species. 

 PcnucUa Okkn, Lehrbuch Naturgeschichte, 1816, p. 3138. Type, P. dlodon- 



tis, monotypic, a synonym of P. sagitta. 

 Lerncopcnna Blainville, Journ. de Physique, 1822, vol. 93, p. 378. Type, 



L. bocconii, first species. 

 Bacvlus I.uunocK, Trans. Linn. Soc. London, 1860, vol. 23, p. 190. Type, 



B. clnngatus monotypic. A larval form of Pennella. 

 EcsscUn BnADY, Challenger Copepoda, 1SS3, vol. 8, p. 136. Type, U. 



Cylindricn, nionotypic. A larval form of Pennella. 

 Pcnclla, Pcnellus, Lernaeopinna, various authors. 



Reasons for retaining the name Pennella. — Linnaeus, mistaking 

 entirely the nature of these parasites, placed them in the genus 

 Pennatula or Sea pens, and this genus name was subsequently used 

 by Ellis (17G3), Gmelin (1788), Lamarck (1818), Pallas (l772), 

 Cuvier (1817), and others. 



