328 CEYLON PEARL OYSTER REPORT. 



Polycarpa, sp. Plate VI., fig. 23. 



External Appearance. Body oblong-ovate with a dorsal projection ; posterior end 

 pointed ; branchial aperture on anterior end, atrial on dorsal edge about one-third 

 of the way back. Surface covered with sand and shell fragments. Size, about 

 6 ceiitims. x 3 centims. 



The single specimen dredged at Tampalakam, Trincomalee, on February ] 1, is found 

 on examination to be in bad condition, so that the internal structure cannot now be 

 determined. It was probably dead when collected. The test is quite stiff and is 

 strengthened by embedded sand. The mantle is thin and appears to have few muscle 

 bundles. The branchial sac is slight, but beyond the four folds on each side little can 

 be made out. There are numerous small polycarps scattered over the body- wall. 



It is impossible to identify this with any described form, and the condition prevents 

 it from being described as new. But it may be useful to place on record that a 

 Polycarpa with these general characters (fig. 23) was found at Trincomalee. 



Family : POLYSTYELID^E. 



Some writers, led by Michaelsen, have of recent years substituted a new term 

 " Polyzoidte " for the above well-known family name Polystyelidse. I cannot follow 

 them. Even if it be proved that Lesson's " Polyzoa opuntia" is the same animal 

 that Cunningham described later as Goodsiria coccinea, it by no means follows that 

 because Goodsiria becomes Polyzoa, Polystyelidse must become Polyzoida?. The 

 type-genus of the family Polystyelidse is, of course, not Goodsiria, but is Polystyela. 

 But it is premature to change even the generic name. It is by no means certain that 

 Lesson's "Polyzoa" belonged to this family. His description would apply at least 

 as well to a species of Colella, such as one resembling the " Aplidium peduncidatum" 

 of Quoy and Gaimard, which is found in the same neighbourhood (Straits of 

 Magellan and Falkland Islands) as to Goodsiria coccinea. 



Michaelsen has recently asked* why Heller's term Polycynthias should not have 

 priority over Polystyelidse as the name of the family or sub-family. The answer is 

 simply because Heller did not propose that term as the title of a family or sub- 

 family, nor did anyone else, until Michaelsen, in 1904. According to the ' Inter- 

 national Rules of Zoological Nomenclature' (Paris, 1905): "Art. 4. The name of a 

 family is formed by adding the ending ido?, the name of a sub-family by adding inoB, 

 to the root of the name of its type-genus." Heller did not do that. He formed no 

 family or sub-family. He merely remarked that the group Cynthiee fell into simple 

 and compound forms (Monocynthiae and Polycynthise). There was no question here 

 of naming or defining a family or a sub-family. No family for this group of genera 

 existed previous to 188G. In that year, in the 'Report on the "Challenger" 

 Tunicata,' Part II., I formed and defined the new family Poly sty elida;, choosing as 



* ' Deutsche Tiefsee-Expedition, 1898-1899,' Bd. vii., 1904. 



