CETACEA 423 



solid cylinder. The same porpoise yielded the flukes already 

 described (D. Campula) . As afterwards remarked in my treatise 

 on the ' Entozoa ' (1864), four of the tapeworms measured, respec- 

 tively, from 7' to lO' in length, the fifth example being relatively 

 small (18" only). For a full description of the worm I must 

 refer either to the Linnean ' Transactions ' or to my introductory 

 volume whence the figures here given are taken. Five of the 

 finest examples of this remarkable cestode have been added to 

 the small collection of entozoa which I prepared for the Museum 

 of the Middlesex Hospital Medical College. The head of this 

 large cestode is excessively minute. The same cetacean host 

 not only yielded these new cestodes and flukes, but also great 

 numbers of the well-known strongyloid lung-worms, called 

 Prosthecosacter inflexus and P. convolutus. Another species 

 (P. minor or Pharurus minor) also infests the porpoise, and a 

 fourth (P. alatus) the narwhal. As I have elsewhere observed 

 (' Entozoa,' p. 91), the three first mentioned forms are readily 

 distinguishable from each other by their relative size and length, 

 and also more especially by the form of the tail. The females 

 of P. inflexus attain a length of nine inches, and those of 

 P. convolutus may be upwards of \\" in length, whilst those of 

 P. minor do not exceed an inch. The species described by 

 Leuckart, from Monodon monoceros, is only half an inch long. 

 All the forms infesting the porpoise were met with by Professor 

 Quekett, and one of them has been carefully anatomised by 

 Professor Busk. Probably several other species will be dis- 

 covered when the lungs and cranial sinuses of the larger cetacea 

 are carefully examined for this purpose. The form (P. convo- 

 lutus) here represented is the least known of the three infesting 

 the porpoise. This species has been dissected by Kuhn and 

 Eschricht, whilst the other species have not only been examined 

 by these authors, but also by Raspail, Dujardin, Yon Siebold, 

 Van Beneden, Leidy, and several other helminthologists. 

 Some of Professor Busk's examples of the male worm (P. 

 convolutus) were fully fifteen lines long, yet, from the condi- 

 tion of the internal reproductive organs, he was led to believe 

 that they were not quite fully grown. I cannot here repeat 

 the anatomical details given in my former work, but I may add 

 that all the species of this genus reproduce viviparously. If 

 the worms are examined in the fresh state the young may 

 occasionally be seen escaping by the vagina. Professor Van 

 Beneden noticed this phenomenon in Prosthecosacter inflexus, 



