CALAMOCRINUS DIOMED E I 1 



pinnule, the second fork on the same side to the third pinnule, the third 

 fork on the lefl to the second pinnule. In the righl anterior food groove, 

 the first fork leads to the fourth pinnule; the second branch, the poste 

 rior interradium, leads to the first pinnule, the third to the second, and 

 the Eourth to the third pinnule. In the righl posterior, the firsl fork leads 

 to tin' firsl pinnule, the second fork <>n the same side to the third pin- 

 nule, the third fork on the opposite side to the second pinnule, and the 

 fourth fork to the fourth pinnule. In the lefl anterior groove, the firsl 

 fork to the left leads to the second pinnule, the second fork mi the oppo- 

 site side to the lii'st pinnule ; the third fork on the same side as the firsl 

 fork leads to the fourth pinnule. In the left posterior groove, the firsl 

 fork leads to the first pinnule, the second fork to tin- third pinnule, tin' 

 third fork to the second pinnule, the fourth fork to the fourth pinnule.* 

 The first and second forks encroach upon the left posterior interradium, 

 the third on the anal. The joints of these lower firsl pinnules form a 

 solid arch over the food groove, bending as they do closely upon the 

 surface of the ventral disk, and are in marked contrast to the other 

 pinnules along the arms and its forks, in which only one or two joints 

 cover the continuation of the perisomatic plating along the sides of the 

 arms. Compare Plate IV. Fig. 1, and Plate Y. Figs. 1. 2, 1, with Plate V. 

 Figs. 5, 6, 7. 



De Loriol f says, " Nous iguorons encore comment s'operait l'occlusion de 

 la cavite qui renfermait Ies parties molles de l'animal. II parait fort proba- 

 ble que cette cavite etait recouverte non d'une voute solide, comrne dans 

 la plupart des Crinoids paleozoiques. mais d'une membrane fortifiee par de 

 nombreuses petites pieces calcaires qui lour donnait de la fermete." 



A few years later, de Loriol confirms this.; for in 1887 he figures (Plate 

 III. Figs. 1, l a "*) the ventral disk of A. Roissj-anus, so that we have for 

 the first time an accurate idea of its structure. The conical sac figured 

 by de Loriol is covered with plates irregular in outline, thin, contiguous, 



* Carpenter in a letter calls attention to a curious point of resemblance between Metacrinus and 

 Calarhocrinus in the characters of the disk. In both cases the ambulacra of the lower pinnules start 

 directly from the primary trunk, and not from its two forks, as in most Crinoids. See Plates 39 and 

 43 of the Challenger Report. 



f Note sur le Genre Apiocrinus. Association francaise pour l'Avancement des Sciences, Comptes 

 Rendus de la 11™ Session, p. 333 (p. 334). La Rochelle, 1882 (Paris, 1883) 



J Note sur quelques Echinodermes fossiles des Environs de la Rochelle. par P. de Loriol. p. 313. 

 Academie de la Rochelle, Societe des Sciences Xatuielles de la Charente Inferieure. Annales de 1886, 

 Tom. XXIIL. 1887. 



6 



