Mr. R. M f An drew on the Comparative Size of Mollusca. 311 



Genus PSYTTALIA. 



Foem. Corpus convexum, glabrum, latiusculum. Caput transversum, 

 thorace non latius. Antennae graciles, filiformes, corpore lon- 

 giores ; articuli breves. Scutum subcarinatum. Abdomen ellip- 

 ticum, subsessile, thorace paulo longius non angustius. Oviductus 

 brevis. Pedes breviusculi. 



Male. Body convex, smooth, shining, rather short and broad. 

 Head transverse, as broad as the thorax. Antennae slender, fili- 

 form, longer than the body ; joints short, numerous. Scutum 

 with a slight keel. Abdomen elliptical, subsessile, as broad as the 

 thorax and rather longer. Ovipositor shorter than the abdomen. 

 Legs rather short. Fore wings rather broad ; veins in structure 

 somewhat resembling those of Pygostolus, to which genus the 

 following species seems to be nearly allied. 



PSYTTALIA TESTACEA. Foem. Testacea, mandibulis apice nigris, 

 antennis piceis, basi testaceis, oviductus vaginis nigris, alis cine- 

 reis, venis nigris, stigmate pallide piceo. 



Female. Testaceous. Mandibles with black tips. Antennae 

 piceous, testaceous at the base. Sheaths of the ovipositor black. 

 Wings cinereous ; veins black ; stigma pale piceous. Length of 

 the body 2 lines ; of the wings 4 lines. 



[To be continued.] 



XXXVI. Reply to Mr. Jeffreys'^ Remarks on a "Note on the 

 Comparative Size of Marine Mollusca in various Latitudes of 

 the British Seas." ' By ROBERT M f ANDREW, F.R.S., F.L.S. 



MR. JEFFREYS, in the wish to substantiate his proposition that 

 " in general, the size of specimens (of Mollusca) increases in a 

 ratio inverse to their northern and converse to their southern 

 points of latitude," having thought fit to contradict some of my 

 statements, and endeavoured to throw discredit upon others, I 

 feel called upon, very reluctantly (anything in the shape of con- 

 troversy being opposed alike to my habit and inclination), to 

 revert once more to the question, in order to show that such a 

 proposition not only has not been proved, but is at variance 

 with fact. 



I cannot boast the advantage of having dredged in extreme 

 northern or southern latitudes, my researches having been con- 

 fined within about forty-two degrees of latitude, or some ten 

 degrees north and twenty degrees south of the extreme limits 

 of the British seas ; but trust that my opportunities have been 

 such as to make me competent to form an opinion upon the 

 point at issue, the conclusion I have come to regarding it 

 being entirely the result of personal observation. 



