PARACALANID^E. 127 



Fam. 2. PARACALANID.E. 

 PARACALANUS PARVUS (Glaus). 



1863. Calanus parvus, Glaus, p. 173, pi. xxvi. figs. 10-14. 

 1901. Paracalanus parvus, G. O. Sars, p. 17, pis. viii., ix. 



This species, though not very plentiful, appears to be more 

 or less generally distributed, and has been obtained in several 

 gatherings. It occurred in a plankton sample from Plymouth 

 Sound, and in another collected about two and a half miles 

 off Plymouth Breakwater. It was also taken near Eddy- 

 stone Lighthouse and at Fowey. Dr. Gr. C. Bourne recorded 

 Paracalanus parvus as " not rare " at Plymouth in 1888- 

 1889 (n. s. vol. i. p. 145). 



PARACALANUS PARVUS, var. PERPLEXUS, nov. var. (Pis. XII. 

 figs. 1, 2 ; XIII. fig. 1 ; XIV. fig. 1.) 



A single female specimen of a Paracalanus was obtained 

 in one of the tow-net gatherings from Plymouth, w r hich, 

 while having a general resemblance to Paracalanus parvus, 

 Glaus, exhibited a rather marked peculiarity in the structure 

 of the fifth pair of thoracic feet. 



In Paracalanus parvus the fifth pair of legs in the female 

 are alike on both sides and very small ; they each consist of a 

 single narrow joint about four times longer than broad, and 

 they each bear two setae at the apex, one being of moderate 

 length, the other very small. In the specimen under con- 

 sideration the right leg of the fifth pair is similar to those in 

 the female of Paracalanus parvus, but the left differs in 

 being two-jointed and considerably elongated. The first 

 joint is moderately and slightly dilated, the second is narrow 

 and about double the length of the right leg ; this greater 

 elongation of the left leg was so prominent that it could be 

 observed even without dissection. A drawing of the fifth 

 pair is shown on Plate XII. fig. 2. Other drawings of this 

 variety will be found on Plates XI \., XIII., & XIV. 



As this specimen does not appear to differ very much 

 from a typical female of Paracalanus parvus except in the 

 structure of the left leg of the fifth pair, and as no other 

 specimens similar to it were observed in the various samples 

 examined even though carefully sought for, it may be merely 

 an abnormal form of the species named. Still, as the specimen 

 appeared to be full grown, it may possibly represent a distinct 

 variety, and we therefore propose to distinguish it from the 

 typical form by the varietal name perplewus. 



