KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 481 



The genus Erijfhropsis is the most highly specialized of all the Gyinnodi- 

 nioidae as shown in acr'ossory ]iai-a('ingnlar grooves along the girdle, the apical 

 horn, the ocelhis, and the complete integration of its constituent lens and pig- 

 ment mass and in the prod with its functional specialization. The ocellus and 

 prod alike attain a degree of structural complexity and diversity in the genus 

 luiequaled among all of the Protozoa. As an organ adapted in structure to 

 the performance of specific function the ocellus is of the same order of magni- 

 tnde, though not of dimensions and cellular components, as the ocelli of the 

 Hydromedusae, Turbellaria, and Rotifera, and the tentacle or prod is in like 

 manner structurally comparable to those of the simpler Hydroida, though not 

 their equivalent in function. The organization of the living substance into 

 organs for bodily functions is evidently, in the light of these extraordinary 

 structures of this unicellular organism, not a function of the number of nuclei, 

 but rather of the organism (ts a whole. The cell theory as a basis of organization 

 breaks down when we attempt to apply it to the organs of the Protozoa. 



Distribution 



The species of Erythroptiis thus far discovered have all l)een found in warm 

 temperate to subtropical oceanic seas under strikingly similar conditions. The 

 eight species discovered at San Diego, in the summer of 1917, were all taken 

 within a period of three weeks and at the same locality. In some instances 

 several species were taken in the same five-inch net. We have found no evidence 

 of either seasonal or geographical isolation of these species. The possibility of 

 a vertical stratification within the eighty meters traversed l)y our collecting nets 

 is, however, not excluded hx our data, but seems highly improbable. 



Historical Discussion 



The history of this remarkable genus is as complicated as its own extraor- 

 dinary combination of organs, and involves one of the most instructive contro- 

 versies in the history of the biological sciences in the past century. It illustrates, 

 on the one hand, the value of the scientific caution of the original describer, 

 and. on the other, the recklessness of his critic and the resulting dojith of error 

 into which his un))ridled zeal for exposure carries him when, without having 

 seen the object under discussion, he ventures to discredit the work of another. 



The genus was described by Professor Richard Hertwig (1884), who found 

 a single individual in the })lankton of the Mediterranean at Sorrento, Italy, in 

 the Easter vacation. Upon placing it under the cover glass for examination it 

 dropped olf its tentacle, whereui^on it was at once fixed in osmic acid and stained 

 and mounted. Professor Hertwig's account of this remarkal)le organism was 

 therefore based upon his recollection of a brief glimpse of the active animal 

 under a low magnification and a closer study of its nnitilated nnd somewhat 

 distorted remains. His conclusions, as to the relationship of this bizarre animal, 

 were that it was undoubtedly a protozoan and one of the Infusoria, although 



