290 J- Playfair Mc Murrich, 



witli stroiig, though iiarrow pennons (Fig. 84) and witli mesenterial 

 filaments. In ten pairs the attachment to the stomatodaeiim extended 

 somewhat further down tlian the others, and their miiscle pennons 

 were a little strenger. These pairs I take to represent the primary 

 cycle, and they included two pairs of directives, which, like the 

 siphonoglyphs , were placed imsymmetrically , six pairs of perfect 

 mesenteries intervening between them on one side and thirteen on 

 the other. There were thus twenty-one pairs of perfect mesenteries, 

 eleven of which seemed to represent a second cycle. The third cj'cle 

 consisted of fourteen pairs of small imperfect mesenteries, destitnte, 

 as a rnle, of filaments and muscle pennons, although a few showed 

 indications of a pennon. It is needless to say that this cycle was 

 incomplete; where present its members altern ated with those of the 

 older cycles. 



The perfect mesenteries possessed a parieto-basilar muscle which 

 formed a distinct fold and extended distally as far as the upper 

 third of the coliimn. The basilar muscles were well developed, con- 

 sisting of a lamella arising from each side of the base of each perfect 

 mesentery and giving rise on one surface to secondary lamellae, so 

 that each may be said to be half-pinnate. Reproductive cells w^ere 

 observed on some of the mesenteries of the first cycle, but they 

 were not sufflciently developed to determine their complete distri- 

 bution. 



It should be stated that all the mesenteries are narrow compared 

 with those of other Cribrinids ; in sections through the column below 

 the level of the stomatodaeum they form a narrow fringe around 

 the inner surface of the wall, leaving a large central cavity, while 

 above they keep the walls of the stomatodaeum widely apart. 



Suborder Stichodactylinae Andres, 1883. 



Actiniaria with simple, capitate or Compound tentacles, arranged 

 in radiating rows, more than one tentacle communicating with some 

 or all of the endocoels or exocoels. 



Family Corynactidae L. Agassiz, 1859. 



Stichodactylinae with a marginal alternating cycle of capitate 

 tentacles and with one or more accessory disc tentacles corresponding 

 with a greater or less number of the marginal ones and of a similar 

 form. 



