AN ALASKAN CORYMORPHA-LIKE HYDROID. 



B}- Samuel Fessenden Clarke, 



Professor of Natural Hhtonj, Williams College, Massachusetts. 



In a report on the hydroids of Alaska, published by the Academy of 

 Natural Sciences in Philadelphia in 1876, the material of which was 

 collected by parties under the charg-e of William 11. Dall, and is now 

 deposited in the United States National Museum, I created the family 

 Rhizonemida^, provisionally, and the genus Rhizuiiema for two some- 

 what nuitilated specimens. Upon further examination, and with 

 opportunity to consult a wider range of hydroid literature, 1 find that 

 I was in error. The specimens belong- either to the genus Coryinorplia 

 or to the genus Lampra., but they are not sufficientl}- well preserved 

 to determine whether the gonophores are of the medusoid type char- 

 acteristic of OorymorpJia^ or of the pseudomedusoid type of Lampra. 

 The h^^drocaulus is smallest just below the In-dranth, enlarging grad- 

 ually to near the base, where the basal filaments begin, and then tapers 

 rapidly to a small rounded end; a small section of the stem innnediatoly 

 above the filaments is roughened with transverse wrinkles. The mem- 

 brane which bears the filaments has something of a mammillated sur- 

 face and is easil}' freed from the cone-shaped base, see figs. 1, 2. The 

 hydranth is large; the proximal tentacles are in a single verticil; the 

 distal tentacles are short, very numerous, matted together, and I can 

 discover in them no regular arrangement. The proboscis is very large, 

 being but slightly smaller at the distal than at the proximal end; the 

 mouth is correspondingly large, the full width of the distal end of the 

 proboscis. Immediately above the proximal tentacles are the peduncles 

 of the gonophores; they are about thirty in number, and l)esides those 

 forming the circle there are a few which originate a little higher up 

 on the proboscis. The peduncles vary nuich in length in this imper- 

 fect, alcoholic specimen; they bear irregular clusters of processes, 

 the gonophores, figs. 1, 3. These specimens were collected in Norton 

 Sound, near St. Michael, Alaska, October 17, 1875, ])y L. M. Turner, 

 of the U. S. Signal Service, who writes that 'Hhesc specimens were of 



Proceedings U. S. National Museum, Vol. XXVI-No. 1343. 



953 



