G THE HYDKOIDS. 



Br., 61° 23.6' W. L. Dr. Kepes; Yellow Sea, Dr. Swoboda; North Atlantic, 

 Bonnevie ; Coast of Maine, Verrill ; Alaska, Clarke. 



It is interesting to find that two of the species, Thuiaria tubuliformis and 

 Zygophylax chazaliei, were known hitherto from the Atlantic side of the 

 Isthmus of Panama only. In 1888 Mr. Alexander Agassiz discussed the 

 resemblances of these two marine faunas, as shown especially by the results 

 of his deep-sea dredgings, in his volumes on " Three Cruises of the Blake," 

 page 157 : " In fact, the deep-sea fauna of the Caribbean and of the Gulf of 

 Mexico is far more closely related to that of the Pacific than to that of the 

 Atlantic. Before the cretaceous period the Gulf of Mexico and the Carib- 

 bean were undoubtedly in freer communication with the Pacific than with 

 the Atlantic Ocean ; so that, notwithstanding the presence of a number of 

 Atlantic types, the characteristic genera were common to the Pacific." 



The label in the bottle with Campanulina denticulata records a depth of 

 2845 fathoms, something unusual, but not unequalled, for hydroids. Allman 

 gives records of 2900 fathoms in the Pacific for Styladis vermicola, and for 

 Monocaulis imperator, collected by the " Challenger." 



Pennaria pacifica, sp. nov. 

 Plate 1. 

 Troposorne : — Hydrocaulus 20 to 35 mm. high, simple, black near the 

 base, becoming horn color at the distal ends, divided by nodes into rather 

 short internodes without annulations in the distal portion, with one, rarely 

 two, in the basal part; pinnae arranged alternately, one from each node, 

 originating below the internode, divided by nodes like the stem and with 

 two or three annulations at the base ; peduncles borne on the upper sides of 

 the pinnae, one proximally to each node, tapering but slightly to the base, 

 where there are two or three annulations. Hydranths with twelve to four- 

 teen filiform tentacles, and when fully developed having about sixteen capi- 

 tate tentacles, somewhat irregularly arranged. 



'Gonosome : — Not present. 



Habitat : — Perico Island. 



These specimens resemble P. symmetrica, but a careful comparison of the 

 specimens of both species shows constant differences in the character and 

 number of the annulations and in the shape of the peduncles, which makes 

 it easy to recognize each kind. In P. symmetrica the annulations are more 



