28 Vniversitij of California Publications in Zoology [Vol. 16 



The eytosome in G. muris is also less distended to the periphery of 

 the body than in G. microti. 



It differs from Lamblia intestinalis (Lambl) in the somewhat 

 smaller size, 10-16 /a as compared with 10-25 /u, and in the marked 

 difference in the parabasals, which are slender and curved in G. 

 microti, bnt nnich larger and massive and apparently fused in one 

 body, according to Bensen (1908) in the former, though Prowazek and 

 Werner (1914) figure a single "Kolbenkorper" stating erroneously 

 that it is on the ventral side of the axostyle. They mention its 

 divi.sion "in mehrere Spangen" in old individuals. The figures of 

 Rodenwaldt (1912) leave little doubt that there are at times, at least, 

 two .stout, brush-shaped parabasals in an obliquely curved position 

 dorsal to the axostyle. These are very much like those of G. microti 

 except that they are a little stouter and le.ss curved. 



Since the specific name intestinalis was preoccupied in the genus 

 Cercomonas by Diesing's (1850) reference of Bodo intestinalis to that 

 genus, Lambl 's (1859) use of the name for the species from man is 

 invalid and no other available name remains. To preserve as far as 

 may be, a clue to its past nomenclatural history, the name Giardia 

 lamblia Stiles in litt. is here proposed for the species hitherto generally 

 known as Lamblia iiitestinalis (Lambl) from man. 



From G. agilis Kunstler (including G. alata Kunstler and Gineste) 

 it differs in the shorter, stouter body and less con.striction of the region 

 of the eytosome from that of the elongated body behind it. The 

 ventral cup forms only 0.20-0.25 of the total length in G. agilis and 

 nearly 0.5 in G. microti. 



Zoological Laboratory, University of California, 

 Berkeley, California. 



Transmitted October SI, 1915. 



