620 



are incomplete, and, as will be shown in the following 

 historical review, any arranj^emeut of the three worms 

 can be looked upon at present only as provisional. 

 The historical review is given in detail, as these three 

 (()!• one?) species represent very important parasites. 

 Molin (1858, p. 139) first described as Taenia tetra- 

 gona some tapeworms which he found in chickens in 

 Padua in December, 1857, as follows: 



Caput tetrag-onum, minimuTn, acetabulis quatuor angularibus, 

 alveolo ad basim rostelli excavatum; rostellum inerme, brevis- 

 simum, obtuso-conicum. in alveolum retractile; collum breve; 

 articuli supremi brevissimi; rnstremi subquadrati, imbricati; 

 aperturae genitales marg-inales, secundae, in apice papillae 

 prominulae. Longit. 0.012-0.090; lat. ad 0.002. 



Habitaculum. Phasianus Gallus: in intestine tenui, Decembri, 

 Patavii (Molin). 



Like most of Molin's descriptions, this diagnosis gives us but 

 little information concerning the parasite he had before hion. 

 It should be noticed, however, that he (probably erroneously) 

 describes the rostellum! as unarmed, the neck as short (a char- 

 acter of little or no value), the posterior segments subquadrate 

 and imbricate, the genital pores as unilateral, the length of the 

 worm as 12mm to 90mm, breath as 2mm. in other words, there 

 is neither a single distinctive character nor a collection of char- 

 acters given in this diagnosis. In his second paper (1860, pp. 

 254-255; Taf. VII, 5-8) Molin repeats this diagnosis, gives four 

 figures of the worm which are almost useless, except fig. 7, in 

 which the genital pores are figured in the middle of the lateral 

 margin, and in which some irregularly-shaped masses are 

 drawn, which evidently represent egg capsules. He also adds 

 three observations to the effect that he collected 42 specimens 

 from one chicken, of which number only 2 were mature, the 

 others being very small. He describes a mosaic structure of 

 the segment caused by egg capsules, each of which contains 

 from 5 to 20 ova. Although the TOSteHum is unarmed, the form 

 differs in organization from the other unarmed forms. These 

 are all of the characters ever given by Molin to the species, 

 and it must, indeed, be admitted that they are not sufficient 

 to determine any worm with certainty. Molin's diagnosis, 

 without the type specimens, is therefore useless. 



