A ctinaria 



The specimens are well preserved in formaline, but are he ., 



dark greenish brown, so that the internal structure cannot well be seen, 

 stomodseum is visible as a short sac below the mouth, 

 distinct mouth-lobes, unequal in size. 



G 137 



ined with 

 The 

 There are two large 



Fig. 21. Arachnactis brachiolata A. Agassiz. The larva or young of a Cerianthus, probably of 

 C. borealis Ver. A very young stage with but two pairs of the tentacles of the 

 outer row (i, ii), and with rudiments of three tentacles of the inner circle; also traces 

 of 8 mesenteries; much enlarged. Canad. Arc. Exped. C. C. A later stage of the 

 same larva, viewed from opposite sides; three pairs of outer tentacles (i, ii, iii) are 

 now developed, but of unequal sizes; also two pairs of the inner or oral circle, 

 in a rudimentary form ; eight unequal mesenteries are visible and also two pro- 

 minent labial lobes, and the stomodseum. Much enlarged. Drawn by the 

 author. 



Fig. 22. The same. From a very young New England specimen. 

 Emerton. 



Much enlarged. By J. H. 



These stages do not quite correspond in the state of development with 

 similar larvse previously described, but they appear to be identical with the 

 similar larvse found on the northern New England coast. (See Text Fig. 22, and 

 PL XXII, fig. 4). The latter is probably the larva of Cerianthus borealis Ver- 

 rill, a common form in the deeper waters of northern New England, the Gulf 

 of St. Lawrence, etc., and the only species known from the very northern waters 

 of America, but not yet reported from the Pacific coast. 



For additional details concerning Arachnactis brachiolata, see G. S. Kingsley, 

 Description of Cerianthus borealis, Tufts College Studies, No. 8, 1904, with three 

 figures of larvse from Casco bay. Also J. L. McMurrich, The Genus Arachnactis, 

 Journ. Experimental Zoology, Vol. IX, No. 1, 1910, pp. 159-168, fig. 4, (com- 

 pared with other species). Also Journal of Morphology, Vol. V, p. 147, pi. IX, 

 figs. 9-13, 1891. 



