PEN N ELLA OIITHAGORISCI. 153 



millimetres (= about 8^ inches), whereas the adult female 

 from the sun-fish is only 93 millimetres (about 3-f- inches). The 

 head of the young female of the sun-fish Pennella, as shown 

 by Brian, is narrow and subcylindrical, fully three times 

 longer than broad, and the horn-like processes are wanting ; 

 the abdominal appendages are also more or less rudimentary, 

 and the posterior annulations appear to be more distinct. 



The free-swimming larvae of Pennella have a close resem- 

 blance to those of Lemsea branchialis and exhibit the near 

 relationship between these genera. Dr. Al. Mrazek, in a 

 paper " Ueber Bacculus Lubb. und Hessella Br. Ein Beitrag 

 zur Anatomie der Lernasiden," * gives a detailed description 

 of the anatomy of these larval forms. 



Pennella balsenopterse Koren & Danielssen. 



Specimens of a giant species of Pennella found attached to 

 a finner whale [Balsenoptera musculns (Linn.)) were presented 

 to Sir William Turner, F.R.S., Edinburgh, by Mr. Chr. 

 Castberg, the manager of a Norwegian Whaling Company 

 which has a fishing-station at Ronasvoe, in the north of 

 Shetland. A full and interesting description of the species, 

 illustrated with four plates, is published by Sir William 

 Turner in the ' Transactions of the Royal Society of Edin- 

 burgh/ vol. xli, Part 2 (No. 18), 1905. 



This somewhat remarkable species does not come within 

 the scope of a Monograph devoted to the parasites of fishes, 

 but we nevertheless refer to it here on account of the author's 

 interesting remarks on the history of the peculiar genus to 

 which the species belongs, and because the description given 

 of the species is also generally applicable to the one found on 

 the sun-fish. 



The largest specimen obtained by Sir William Turner 

 measured 294 mm. (nearly 11 A inches) in length, but, as 

 the author remarks, even larger specimens have been recorded 

 by Koren and Dauielssen ; one of these is said to have 

 measured 320 mm. (12^ inches) in length. In this species the 

 head is provided with three slender chitinous horns of unequal 

 length which extend horizontally outwards at nearly right 

 angles to the body, the dorsal horn being usually the shortest ; 

 and in this and a few other respects Pennella bahenopterse- 

 differs from the sun-fish parasite. It seems however to be 

 still a moot-point whether all these different Pennellse are to 

 be regarded as valid species. 



* ' Sitzung-sberichte d. koni» - l. holnn. (lesellsch. d. Wiss./ Math.-nat. 

 Classe ( L895), xliv, pp. 1-17, 2 plates. 



