28 MEDUS.E OF THE WORLD. 



H ydroid. The stems are 60 to 80 mm. long, zigzag, and with 15 to 20 alternate branches. 

 The longest branches are nearest the base and are about 12 mm. long. There are about 8 

 hydranths, 1.7 mm. long, on each branch. These hydranths are slender, the proximal ones 

 only about half as large as the distal primary one on each branch. There are 2 verticils of oral 

 tentacles, each with 4 tentacles alternating in position with those of the other row. These 

 oral tentacles are short and each ends in a nematocyst-knob. The uppermost row of 4 oral 

 tentacles is in the 4 perradii, and the lower row in the 4 interradii. There are 24 long 

 filiform tentacles in a single row at the broad base of the polypite. These are about as long 

 as the polypite itself. The perisarc of the hydrorhiza and main stems is opaque and black, 

 and the side branches are yellow. The hydranths are white. 



Coast of New South Wales, Australia. Medusae are produced in March. 



This species is distinguished by the minute ectodermal ocelli upon the tentacle-bulbs 

 of the male medusae, and by the length of its tentacles. There are also but 2 verticils of 

 oral tentacles. 



Pennaria pacifica Clarke. 



Pennaria pacifica, CLARKE, 1907, Mem. Museum Comp. Zool. Harvard Coll., vol. 35, No. l, p. 6, plate I, figs. 1-6. 



Hydrocaulus 20 to 35 mm. high. Internodes of the main stem without annulations at 

 their distal ends, and with only I or 2 rings at their proximal ends. Branches alternate. 

 Peduncles taper slightly to the base where there are 2 or 3 annulations. Hydranths with 

 12 to 14 filiments, and about 16 capitate tentacles somewhat irregularly arranged. 



Pinco Island, Gulf of Panama, tropical Pacific. 



Distinguished only by its few annulations at the internodes of the main stem. It is 

 probably only a local variety of P. tiarella. 



Pennaria ? vitrea Agassiz & Mayer. 



Pennaria vitrea, AGASSIZ and MAYER, Bull. Mus. Comp. Zool. at Harvard Coll., vol. 32, p. 161, plate I, figs, l, 2. 



Bell is 3 mm. in height; walls thick and rigid. There are 4 rudimentary tentacle-bulbs. 

 Velum not prominent. The 4 radial-canals are straight and narrow. The manubrium in the 

 female specimen was retracted within the cavity of the bell, but it was flask-shaped in the 

 male and projected for a short distance beyond the velar opening. These conditions, how- 

 ever, may be merely different states of contraction and not constant differences; but as we 

 observed only two individuals, one a male and the other a female, we can not be certain upon 

 this point. The ova are large and pyriform, and are grouped in 4 interradially arranged 

 clusters within the manubrium. The mouth-opening is simple, and there are no fimbriations 

 or appendages. 



Prominent circular muscles were observed in the ectoderm ot the cavity of the bell in the 

 female, but these were not seen in the case of the male. It is possible, however, that they 

 become apparent only during certain states of contraction. In the female the ova and tentac- 

 ular bulbs were flesh-colored, and the entoderm of the mouth was green. In the male the 

 tentacular bulbs were green, the entoderm of the manubrium pink, and the lips green. 



Found among the Fiji Islands, off Kimbombo Island, November 25, and ofF Mbatiki 

 Island, December 5, 1897. 



Not having seen the hydroid I am very doubtful concerning the generic identity of this 

 medusa with Pennaria. 



Genus TRICHORHIZA Russell, 1906. 



Trichorhiza, RUSSELL, 1906, Proc. Zool. Soc. London, p. 99, plate 5. 



GENERIC CHARACTERS. 



The medusa is similar to that of Pennaria, but with one tentacle-bulb somewhat better 

 developed than the 3 others. The hydranth is solitary, with a branched, filiform hydrorhiza. 

 The perisarc forms a cup into the cavity of which the hydranth may be partially retracted. 

 There are 2 verticils of tentacles, an oral and a basal; and the medusa-buds arise from the 

 sides of the hydranth between these 2 verticils. The type-species is Trichorhiza brunnea 

 Russell, from the Firth of Clyde, Scotland. 



