In other cases, however, the medusa-individuals become sexually mature while still attached to the parent polyp, and are then not set free at all, but become appanages of the hydroid colony and undergo degenerative changes leading to reduction and even to complete obliteration of their original medusan structure.
Numerous Catholics, on the other hand, well qualified to form a judgment, themselves protest against this obliteration of the dividing line.
The ganglia are crowded at the posterior end of the body as in leeches, and there is much tendency to the obliteration of the coelom as in that group. Pterodrilus and Cirrodrilus bear a few, or circles of, external processes which may be branchiae; Bdellodrilus and Astacobdella have none.
The English expeditions of 1544 and 1545 were exceptionally disastrous, since they involved the destruction of the four Scottish border abbeys, the sack of many towns, and the obliteration of Roxburgh.
Tentacles are hollow; but in some cases the tentacle may become solid by obliteration of its cavity.
In the numerous degenerate forms simplification occurs by obliteration of the demarcations of somites and the fusion of body-regions, together with a gradual suppression of the lamelliferous respiratory organs and the substitution for them of tracheae, which, in their turn, in the smaller and most reduced members of the group, may also disappear.
These improvements connote the obliteration of the insanitary and overcrowded courts and alleys which were to be found between all the main streets, few in number, connecting the upper and the lower towns.
Of the highly developed civilizations which grew up and flourished in Bactria, Bokhara and Samarkand the last survivals are now undergoing rapid obliteration with the simultaneous desiccation of the rivers and lakes.
This concentration and obliteration of somites, often accompanied by dislocation of important segmental structures (such as appendages and nerveganglia), may lead to highly developed specialization (individuation, H.
Concentration of the organ-systems by fusion of neighbouring regions (prosoma, mesosoma, metasoma), pre viously distinct, has frequently occurred, together with obliteration of the muscular and chitinous structures indicative of distinct somites.