NO. 1123. PROCEEDINGS OF THE NATIONAL MUSEUM. 819 



and neck of the embryo were released was the most changeable, its 

 walls being well supplied with contractile tissue. 



Dimensions of alcoholic specimen: Length of posterior elongated 

 portion, 7.1 mm.; diameter of same, 0.9; diameter of globular anterior 

 l)ortion, 1.5; breadth of head of embryo, 0.47; diameter of neck, 0.2; 

 length of longest hooks, 0.08; length of small hooks, 0.013. 



5. Paraiichthys denfatus. — The single specimen which I have from 

 this host presents some differences from tliose from other hosts and may 

 differ from them specifically. A sketch was made of the living specimen, 

 but no other notes made at time of collecting. The sketch shows the 

 usual division of the elongated blastocyst into an anterior subgiobular 

 portion containing the embryo and an elongated i^osterior portion — the 

 latter about three and a half times the length of the former when at rest. 

 When compressed, there is brought into view an interior prolongation of 

 the posterior part, which extends into the anterior portion, occupying 

 about the posterior fourth of that part, while the embryo is confined to 

 the anterior fourth of the same part. Two prominent sinuous vessels 

 are seen in the anterior part lying one on each of the lateral margins — 

 when compressed (fig. 8). Unfortunately the alcohol had evaporated 

 from this specimen when I came to study it for identification, and it was 

 ill very poor condition. The hooks were dark red. This I think must 

 be due to changes with the drying of the specimen, since 1 find no men- 

 tion of such fact among my notes. If the hooks had been red in the 

 living worm, that fact would hardly have been overlooked, although but 

 superficial examination was made of it at that time. The breadth of 

 the head, alcoholic, is 0.46 m. ; diameter of neck, 0.12. The largest hooks 

 are not well shown ; length of such hooks as were seen, near base of pro- 

 boscis, 0.038. This is much less than length of characteristic long 

 slender hooks in this species, but not contradictory of that species, since 

 some hooks near base of proboscis in typical specimens may be found 

 having such diuiensions as this. 



6. Trygon centrura.—Yon\\(\. ou three occasions in this host, where its 

 presence must be regarded as accidental {Xenosite, van Benedeu). One 

 examined as alcoholic specimen; proboscides fully extended and exhib- 

 iting characteristic hooks; at base hooks resemble those figured in my 

 paper in the United States Fish Commission report for 1887 ; elsewhere 

 hooks long and slender, about 0.06 mm. in length; standing nearly at 

 right angles to the proboscis, and having the appearance of being in 

 whorls instead of spirals, with about ten hooks in a whorl. 



The cysts from one stingray were hard, with a yellowish-white gran- 

 ular deposit, appearing to be undergoing degeneration, but with larvae 

 develo])ed in them. 



7. MnsteJus canis. — Found at two different times in this host. Speci- 

 mens identical with those found in sting ray, large hooks slightly bifur- 

 cate; this character also seen in hooks of specimens from other hosts. 

 Measurements of living specimen: Length of cyst, 5 mm.; diameter, 3; 



