l22 PROCEEDINGS OF THE ACADEMY OF [DeC, 



Coe (1895 a), in regard to Cerehratulus lacteus, says : " The amis 

 is at the end of the body, just beneath the caudal papilla." 



Coe (1901) gives as one of the generic characters of Cerebratu- 

 lus, ". . . . the posterior end extremely flattened and provided 

 with a delicate caudal cirrus, which extends beyond the opening 

 of the intestine." 



Wilson C.B. (1900) uses Hubrecht's term "anal papilla" 

 for the caudicle of Cerehratulus lacteus. 



Punnett (1900) speaks of a " caudal appendage." 



11. O. F. Muller (1788) describes and figures, p. 38, tab. 68, 

 figs. 18, 20, a Planaria filaris : " Planaria linearis cauda filiformi 

 contractili." The length of the " cauda filiformis coutractilis " 

 in fig. 20, equal to the length of the body, suggests the thought 

 that it may be the evaginated proboscis. Burger (1895), p. 8, 

 says that this worm is probably a Tetrastemma. 



Grube (1855) describes two new species of Mechelia. The 

 first, M. annulata, resembles the 31. Knerii Diesing. Grube 

 thinks that the " processus terminalis " described by Diesing is more 

 probably a regenerating end ; he says : ' ' Der processus brevissimus 

 filiformis konnte ein reproducirtes noch junges Schwanzeude sein." 

 The second species, M. aurantiaca, has the following character- 

 istics: " Der Korper verschmalert sich nach hinten sehr allmah- 

 lich, und endete bei einem Exemplare in ein viel diinneres, war- 

 scheinlich vor kurzem reproducirtes Schwiinzchen." 



Montgomery (1897 a), Taf. 2, Fig. 16, has described as a cau- 

 dicle what is evidently a regenerating posterior end." The char- 

 acters that make the structure described by Dr. Montgomery in 

 Cerehratulus lacteus, and figured by him on Taf. 2, Fig. 16, a 

 regenerating posterior end rather than a true caudicle are (1) the 

 size, (2) the presence of the alimentary canal, (3) the presence 

 of the outer longitudinal muscle layer, and (4) the presence of the 

 three distinct blood vessels with definite walls. 



The chief external differences between the true caudicle and the 

 regenerating papilla of Cerehratulus lacteus are in size and general 



"My attention was called to this error by Dr. Montgomery himself, who 

 has suggested that it be rectified. Dr. Montgomery has kindly lent me his 

 own preparations upon which the observations were made, so that I have 

 been able to compare them with slides of my own, made from a Cerehratu- 

 lus lacteus found in life with a good -sized regenerating papilla, which bore a 

 short caudicle at its posterior end. 



