314 Miscellaneous. 



character, except that which is incident to the junction of the many- 

 spines which make up the spiculum. Average extent of stellate 

 spicula measured from the ends of opposite rays •001. Rays some- 

 times of uniform thickness, occasionally enlarged at the ends with 

 microspines, curved inward. 



There are also many small spicula with one or two long arms, 

 forming an axis from which proceed other rays or arms perpen- 

 dicular to the axial rays. These are all microspined, sometimes 

 with blunt terminus and sometimes tapering slightly. 



The two kinds of birotulate spicula found in the statoblast of 

 this sponge, as already described, bring it into the genus Hetero- 

 meyenia, Potts. But for this feature it miist be classed at least 

 as a remarkable form of Metjenia plumosa, Carter. Forty years 

 ago Mr. Carter, of England, found his specimen of the last-named 

 sponge in the water-tanks of Bombay, India. This he described iu 

 1849. No other specimen or variety of it was found again till 

 three or four years ago, when Dr. Palmer found a variety of it on 

 the banks of the Colorado lliver. This was described by Mr. Potts, 

 who named it Meycnia plumosa, variety Palmeri. See his descrip- 

 tion in his monograph of the freshwater sponges. 



As the term used to designate the generic character of this 

 entirely new form is technically expressive of one of its peculia- 

 rities, I have thought it best to use a specific term which is also 

 expressive of the stelliform spicula, which, among all the freshwater 

 sponges, so far as I know, are only found in this and the two allies 

 above named. It will therefore be known as Hetcromeyenia radio- 

 sjnculata. 



This sponge was found in the Ohio River, twelve miles from Cin- 

 cinnati, by my fi'iend Mr. George B. Twitehell, in September 1887, 

 and sent to me in November, same year. I acknowledge my 

 indebtedness to Mr. Twitehell for several other specimens found also 

 in the Oliio River. Among them are Carter'ms tubisperma, Mills, 

 a fine specimen of TuheUa potnsylvania. Potts, and Sponr/illa Innis- 

 tris, Auct. — The Microscope, no. 2, February 1888, p. b2 (Detroit). 



On Parasitic Castration in the Eucyp>hotes of the (Jenera Palajmon 

 and Hippolyte. By M. A. Giard. 



In 1837 Rathke noticed the curious fact that the Palasmons 

 infested by Bopyri belonged exclusively to the female sex : — 

 " Mh'uhile dictu Bopyri omnia cpice vidi exemphi — vidi autem eorum 

 plures centurias — solummodo in Pcdcemonibus fcminis repereram, 

 lictt in manus meas non paueiores horum animaliura mares quam 

 femince incidissent'" *. All subsequent authors down to the most 

 recent one, P. Fraisse, have only confirmed Rathke's observation. 



Guided by my previous discoveries as to the effects of parasitic 

 castration in Decapod Crustacea infested by Rhizocephala, I last 



* ' De Bopyro et Nereide,' p. 18. 



I 



