414 Tetrarhynchus erinaceus 
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EXPLANATION OF PLATES XIX-XXIV. 
PLATE XIX. The strobila and scolex. 
Fig. 1. The strobila: mag. 5 dia. 
Fig. 2. The scolex seen from the side: mag. 30 dia. 
Fig. 3. The scolex; nearly dorsal view: mag. 30 dia. 
Fig. 4. Transverse section of the -scolex passing through the posterior region of the 
bothridia. The proboscides are extruded: mag. 75 dia. 
Fig. 5. Transverse section of the scolex passing through the neck at the region of the 
proboscis bulbs. Mag. 94 dia. 
PLATE XX. The proboscis. 
Fig. 6. The proboscis showing one row of hooks. Mag. 580 dia. 
Fig. 7. The proboscis from the opposite side. Mag. 580 dia. 
Fig. 8. One view of a proboscis taken from a plerocercoid worm encysted in the muscles 
of the halibut. Mag. 280 dia. 
Fig. 9. A, B, C, D. The different hooks and spines on the proboscis of the adult worm. 
The numbers beneath the various figures are the actual sizes in millimetres of the 
hooks measured along the diameters represented by the lines and arrows. 
PLATE XXI. The immature proglottis. 
A semi-diagrammatic representation of the organs in the immature proglottis. The 
relative sizes of the various organs are as nearly as possible accurately represented, 
but the vasa deferentia and uterine canal are drawn with fewer convolutions' than 
are actually present. The testicular follicles are represented as less in number than 
those actually present, and for simplicity’s sake those overlying the uterus have 
been omitted. The vitellaria are represented as two marginal bands (but see Text-fig. 8). 
Neither the vasa efferentia nor the excretory canals are represented. The view may 
be either dorsal or ventral since the genital iiit may be situated on either side of 
the proglottis. Mag. 65 dia. 
