CESTODE PARASITES. 



263 



Tlie neck is long and covered with minute spinules, which are not aj)parently arranged in any 

 definite pattern. The scolex is also covered with spinules. In some specimens this spinulation extends 

 for some distance along the strobila, but it is a variable characteristic, and a few specimens sliow hardlj' any 

 sign of it at all. It appears probable that this variation is due to the deciduous nature of the spinules, 

 some of which have probably been abraded off during capture and preservation, because some of our 

 specimens have large spineless patches in the midst of a spiny portion. 



The proglottides, of which over 150 were counted, are broader than long, excepting the last three 

 or foiir, which become slightly longer than broad. The sides are sUghtly convex, and more so in the last 

 few segments. The edges are not salient. Tlie genital pores are lateral and irregularly alternate. The 

 internal anatomy was not investigated. 



The diagnosis of Platyhoihrium spinuUfera, n. sp., is as follows : — 



Small worms, 3-4 cms. long. Head with four sessile bothridia disposed in pairs laterally. Each 

 bothridium is divided into two loculi by a transverse septum, the proximal loculus being twice as large as 

 the distal one. Incipient traces of a second septum were noticed in few isolated bothridia. Each bothri- 

 dium is surmounted by two strongly-curved bifurcated hooks, which are not symmetrical, and the basal 

 pieces of which are markedly unequally developed and are not connected with each other. In addition to 

 the two forks of a suigle hook, there is usually present a thu-d blunt and thick process which arises at 

 the base of the fork. Each bothridium is further surmounted by a fairly large accessory sucker having 

 thickened walls, the four accessory suckers together fornung a squarish proximal pad. Neck long. 

 Scolex, neck, and parts of the strobila covered with minute deciduous spinules. Segments broader than 

 long, except the last three or four. Genital pores lateral, inconspicuous, and irregularly alternate. 



Habitat. — The spu-al valve of Oakocerdo tigrinus, MiiU. and Henle. Forty-four specimens. 

 Cheval Paar. December 14, 1910. 



Linton established tlie genus Platyhothrium on a single specimen, which he named Platybothrium 

 cervimim, and, so far a:} I am aware, no other species of this genus has since been described. It seems 

 fairly certain that the " single indistinct depression (supplemental disc ?) on each bothrium " of this 

 specimen was an accessory sucker. 



Linton's " objection to referring the specimen to the genus Proslhecobothrium is that the apparent 

 homologue of the posterior bothrial appendage, which is characteristic of that genus, is in this (Linton's) 

 specimen to be regarded as a loculus formed by a transverse costa near the posterior end of the bothrium "' 

 eeems well founded, and the genera are not very similar, particularly since definite accessory suckera are 

 now known to be present in the genus Platybothrium and absent in Prosthecobothrium. 



The following hst comprises a few of the distinct characters of the genera included in Bronn's 

 family Onchobothriidce (= Phyllacanthiens , V. Ben.), which may be useful : — 



Accessory Suckers. 



Genus. 

 Onchobothrius 



Callio bo thrium 

 Acantho bothrium 

 Prosthecobothrium 



Platybo thrium 



Phoreiobothrium 



Ceratobo thrium 

 Cylindrophorous 



Hooks. 



to 



Rose thorn shaped, stout, four 



each bothridium in two pairs 

 Four to each bothridium in two pairs 

 Eacli with two bifiu-catod hooks 

 Each witli two bifurcated hooks 



Each bothridium with two strcngly 



bifurcated hooks 

 Each bothridium with two hooks, 



each hook with tluree prongs 

 Absent ? two curved simple hooks . . 

 Each botluidimn with two bifurcated 



or trifurcated hooks 



Bothridium. 



Each with two septa . . 

 Each witli two septa . 

 Each with two septa . 

 Septa absent 



Absent 

 One to three 

 One 



One posterior (not 

 homologous ?) [I 



Each with one septa . . One 



Septa absent 

 Septa absent 



Septa absent 



One 

 One 



Absent 



Taking for granted (as appears likely) that Lmton's specimen possessed accessory suckers,. 

 Platybothrium spinuUfera, n. s])., then diflters from Platybothrium cervinum, Linton, in being only lialf as 

 large ; in possessing minute spinules on the head, neck, and parts of the strobila ; in the shape of the hooks ; 

 and in the proglottides being broader than long (save in the last three or four). 



