204 bulletin: museum of comparative zoology. 



Histioneis josephinae, sp. nov. 



Plate 15, Fig. 91. 



A large species with deeply concave mid body and broad, subcylindrical, 

 posterior collar as in H. helenae. This species is especially marked by the 

 enormous development of the various wings and by the presence in their pe- 

 ripheral portions of arborescent thickenings which resemble a coral necklace in 

 form. In addition to an enormously developed posterior dorso- ventral wing 

 there is also present a pair of transverse wings arising from the posterior rib, 

 and a great accessory lateral on the left side, the latter as well as the ventral 

 wing being provided with an excessively hyaline outer segment. Each of these 

 wings bears one or several coral-like thickenings at the termination of ribs or in 

 peripheral regions. The most striking development of organs of flotation among 

 the Dinoflagellidia. 



Length, 115 fx ; dorso- ventral diameter, including wings, 80 /x. 



Station, 4699. 



Histioneis longicollis, sp. nov. 



Plate 16, Fig. 100. 



A small species resembling immature stages of H. cymbalaria but differs 

 from it in having a more rotund body, a postero-ventral fin deflected ventrally 

 from the axis and without ventral marginal rib. The posterior collar bears a 

 hyaline list on its anterior margin outside of the rib. Both collars are closed 

 both dorsally and ventrally by hyaline membranes. The body wall is not 

 pitted or reticulated. 



Length, 70 fx ; dorso-ventral diameter of body, 24 p. 



Station, 4711. 



Histioneis navicula, sp. nov. 



Plate 16, Fig. 96. 



A medium-sized species with boat-shaped body resembling that of H. cymbal- 

 aria but longer and more slender. The posterior collar resembles that of 

 H. biremis, but both it and the anterior are complete both dorsally and ventrally, 

 there being no gap in the suture line. The anterior collar is asymmetrical, 

 being shorter along the right margin. This collar is somewhat reticulated and 

 ribbed. The ventral fin has a single ventral and one posterior rib, the latter 

 branching at the tip. Phaeosomes in the anterior chamber. 



Length, 86 lk ; dorso-ventral axis of body, 62 ll. 



Station, 4734. 



Histioneis paulseni, sp. nov. 



Plate 15, Fig. 94. 



A small species related to H. remora. It differs from it in having the body 

 more elongated in the dorso-ventral direction, a wider and relatively shorter 



