6 NEW INVEETEBRATA FKOM 



of the spaclix aiul those of the capsule are siniihirly united. 

 Spermatic elements are formed inside the sporosac and are 

 developed from the external walls of the spadix, probably 

 making their way out through an opening in the distal end 

 of the sporosac. The female Atractyloidcs was not ob- 

 served. 



Perigonimus formosus sp.. nov. 



A Perigonimus, which resembles P. serpens Allman, 

 was taken at Santa Crnz. 



# 



Stem small, creeping, sending up at intervals small, 

 chestnut-colored tul)es. No hydrothecal enlargement. 

 Stems simple, branching, slightly annulated. 



Polypites with reddish-yellow hydranths, each with from 

 ten to sixteen tentacles and a prominent circumoral knob. 

 External walls covered with unicellular algse. Tentacular 

 nematocysts prominent. 



The gonosac arises from the creeping stalk and is a cap- 

 sular body found in numbers in different regions of the 

 colony. The ovisac forms at the extremity of a simple 

 tube not unlike that which bears the h^dranth. This tube 

 is slightly annulated and at its distal extremity is enlarged 

 into a spherical body of dark crimson color enclosed in a 

 transparent sac. 



The mode of formation of the ovisac separates this spe- 

 cies of Perigonimus from others which have been de- 

 scril)ed. No medusa was observed and the color is very 

 different from P. seipens. 



It is believed that the ovum after segmentation devel- 

 ops into a planula in its sac, and separating from this 

 organ follows a similar course of development in one or 

 two other genera of hydroids. If this supposition be cor- 

 rect, this is an exceptional method of development for this 

 ffenus. 



