170 Introduction to Animal Morphology. 



C. serialis is a similar scolex in rabbits. E. acanthorhynchus 

 a short, oval form, from the intestine of the black-necked 

 Grebe, has a long rostellum with 8-10 rows of hooks. As 

 Leuckaiihd,?, shown that some Taeniae early lost their rostellum 

 and hooks, other divisions of these worms have been pro- 

 posed as Sclerolepidota (with hard egg-shells), and Malaco- 

 lepidota (soft egg-shells) by Weitiland, or Cysticse and Cysti- 

 cercoidae by Z^wc^ar/. Family 2. Dibothria — ^jointed worms, 

 rarely with hooks, and with two opposite suckers on the 

 flattened head, placed somewhat like the sense-grooves of 

 Nemerteans. Bothriocephalus, with its suckers correspond- 

 ing to the margins of the body, includes B. latus, the tape- 

 worm of Europe, east of the Rhine, sometimes thirty feet in 

 length, and with 5-10,000 joints, with wide segments and 

 genital organs opening centrally (marginally in B. longicollis 

 of the fowl) ; the uterus forms a rosette, and the eggs are 

 oval ; within these are developed ciliated proscoleces with 

 six hooks. Under this ciliated integument a cuticle forms, 

 and the ciliary layer is shed ; the scolex is free, aquatic. They 

 are said to abound where lake-water is used for drinking. 

 Dibothrium has its suckers corresponding to the surfaces, not 

 to the margins. D. claviceps, of the eel, and D. probosci- 

 deus, of the salmon, have marginal sex orifices. D. puncta- 

 tum, of flatfish, and D. cordatum, a human parasite in 

 Greenland, with an abundance of calcareous concretions, 

 have ventral openings. Family 3. Diphyllidae — ^jointed ; head 

 W'ith two suckers ; two rostella armed with vertical hooks ; 

 neck bristled. Echinobothrium, a selachian parasite, has its 

 larvae in Crustacea and Molluscs. Family 4. Tetraphyllidae — 

 jointed, with four movable suckers, sessile or stalked ; this 

 group includes three sub-families. Phyllobothrinae, with soft, 

 bookless suckers, selachian parasites. In Echeneiobothrium, 

 the proglottides grow as large as the entire strobile, and the 

 suckers are ridged like those of Echeneis. Tetrabothrium 

 and Anthobothrium also live in sharks and rays. Phyllo- 

 bothrium delphini has been found self-impregnating. Phyl- 

 lorhynchince — neck thin or swollen ; suckers four, and four 

 retractile proboscides armed with hooks. Tetrarhynchus is 

 found mostly in sharks ; its scolex is known as Anthoce- 



