306 



MR. H, A. BAYLIS AND LT.-COL. CLAYTON LANE ON 



Elaphocephalus Molin, 1860. 

 Elaphoce-phalus Moliii (1860, p. 343). 



Genotype: Elaphocej^hcdus octoconiutus Molin (1860, p. 344). 



v.DrascIie(1884,p. 113; 

 pj. iii. figs. 21-23). 



This genus and species, based on a single female from Ara 

 \Psittacus\ macao, are characterized by the possession of four 

 cervical sacs which are without the internal processes found in 

 Ancyr acanthus. As in that genus, there are four freely-projecting 

 external appendages, each of Avhich, however, possesses an 

 external process shorter than itself. The cuticle of the body 

 carries closel3'-set spines. 



Whether Aiicyracanthus pinnatifichis and EUq^Jiocephahts 

 ostocorautus do or do not belong to the Gnathostomidie can only 

 be ascertained after further investigation, but it is not impossible 

 tha.fthe structures just mentioned correspond to the ballonets 

 and cervical sacs of the Gnathosto mince. If this be so, the 

 difference between the sul)fami]y and tiiese two forms presumably 

 lies in r.n exuberant development, in the latter, of the ballonets, 

 unconfined by a stout overlying covering. Jn the forms 

 unquestionably belonging to the subfamily such confinement 

 within a uniform head-bulb is complete in Giiathostom.a and 

 KchcnoceplLalns, less complete in Tanqua anomala and T.cliadema, 

 and least so in Tanqua tiara, in which last the prominences 

 corresponding to the four underlying ballonets are sometimes 

 strikingly distinct. It is not difficult to imagine that further 

 exuberance and external subdivision or indentation of the cuticle 

 covering the ballonets might well produce those external and 

 internal modifications which have been described in these two 

 genera. 



Note. 



Our best thanks are due to Mr. T. Soutluvell, formei-ly Director 

 of Fisheries for Bengal, Bihar and Orissa, for supplying us with 

 much of the material upon which the work has been based, 

 especially as regards the genus Echlnocephalus. 



As regards the nomenclature of the hosts, we are indebted to 

 Mr. Old field Thomas, F.R.S., for verifying a,nd correcting the 

 names of all the mammals mentioned in the paper; and to 

 Mr. C. Chubb, Dr. G. A. Boulenger, F.R.S., and Mi-. 0. Tale 

 Began, F.B.S., for performing the sjime kind ofiice in the cases of 

 ])irds, reptiles, and fishes respectively. 



For the preparation of some excellent serial sections w^e are 

 indebted to the skill of Mr. Cecil Gunns, of the Zoological 

 De])artment, Imperial College of (Science. 



For all errors and omissions we accept full responsibility. 



The figures have all been drawn to scale with the aid of the 

 Abbe camera lucid a. 



The type^specimens of the species described as new are in the 

 Bi'itisli Museum (Natural History). 



