20 DR. BAIRD ON TWO NEW CESTOID WORMS. [Jail. 28, 



14. Caica h^matotis. — Pionus hoematotis, Sclat. et Salv. P. Z. S. 

 1860, p. 300 ; Ibis, 1860, p. 401, pi. 13. 



Playa Vicente. These are the only examples of this Parrot I 

 have seen, except those obtained by Mr. Salvin, who discovered the 

 species in Vera Paz in 1860. 



15. Spatula clypeata (Linn.). 



Cosamaloapam. Noticed by Mr. Salvin as far south as Dueiias, 

 (See 'Ibis,' 1859, p. 231.) 



16. FULIGULA RUFITORaUES, Bp. 



Examples in undress plumage, from Oaxaca. I believe that tlie 

 birds in Senor R. Montes de Oca's collection, which I referred 

 (P. Z. S. 1859, p. 369) to F. affinis, were really of this same species. 



3. Description op Two New Species of Cestoid VV^orms, 



BELONGING TO THE GeNUS T^NIA. By W. BaIRD, M.D., 



F.L.S. 



(Plate II.) 



1. TiENIA AMMONITIFORMIS. (PI. II. figS. 1-7.) 



Head small, somewhat quadrangular ; mouth circular, armed with 

 a single circlet of recurved booklets ; neck nearly of the same size as 

 the head. Body increasing gradually in size as it descends from the 

 neck, with numerous indistinctly formed segments, and remaining of 

 nearly uniform size till it reaches the lower extremity, where it again 

 contracts in dimensions, the segments then becoming regularly taenii- 

 form and flat. 



At first sight this entozoon presents a singular and anomalous ap- 

 pearance. When first taken it was found rolled up in the form of a 

 double helix, with a peculiar hollow in the middle (fig. 1). Each 

 of these helicoid portions, when examined by a low power, presented 

 the appearance of an ammonite (fig. 3). When partially unrolled, 

 it assumed the form of the shell of a species of Siliquaria (fig. 2). 

 The whole body of the animal is hard and rigid, and partially in- 

 curved at the edges, giving the under surface a hollow appearance. 

 The divisions or rings seen on the body are not distinctly formed 

 segments till near the lower extremity, when three or four regular 

 tseniiform segments show themselves, as in other species of the genus 

 Tcenia. The structure of the centre portion of the body is exhibited 

 at fig. 4, but the segmented lower extremity has not been repre- 

 sented. No trace of genital organs was observed. The head (figs. 5 

 and 6) is somewhat tetragonal in shape, and beset on its edges with 

 sparsely scattered and small protuberances. The bothria or suck- 

 ers are of moderate size, and the mouth is terminal, and surrounded 

 with a single crown of amber-coloured recurved booklets, presenting 

 the appearance of siliceous spicula (fig. 7). 



At first sight it is difficult to imagine this anomalous-looking 

 entozoon to be a Tcenia ; but the four bothria or suckers, and the 



